diff --git a/drivers/atmodem/atutil.c b/drivers/atmodem/atutil.c
index fe7cbfc1..b6f0d92a 100644
--- a/drivers/atmodem/atutil.c
+++ b/drivers/atmodem/atutil.c
@@ -133,8 +133,7 @@ GSList *at_util_parse_clcc(GAtResult *result)
 			g_at_result_iter_next_number(&iter, &number_type);
 
 		call = g_try_new0(struct ofono_call, 1);
-
-		if (!call)
+		if (call == NULL)
 			break;
 
 		call->id = id;
diff --git a/drivers/atmodem/atutil.h b/drivers/atmodem/atutil.h
index 7dbb8a6d..39018016 100644
--- a/drivers/atmodem/atutil.h
+++ b/drivers/atmodem/atutil.h
@@ -82,8 +82,7 @@ static inline struct cb_data *cb_data_new(void *cb, void *data)
 	struct cb_data *ret;
 
 	ret = g_try_new0(struct cb_data, 1);
-
-	if (!ret)
+	if (ret == NULL)
 		return ret;
 
 	ret->cb = cb;
diff --git a/drivers/atmodem/call-barring.c b/drivers/atmodem/call-barring.c
index 50e0eefc..c0b1d115 100644
--- a/drivers/atmodem/call-barring.c
+++ b/drivers/atmodem/call-barring.c
@@ -86,7 +86,7 @@ static void at_call_barring_query(struct ofono_call_barring *cb,
 	struct cb_data *cbd = cb_data_new(callback, data);
 	char buf[64];
 
-	if (!cbd || strlen(lock) != 2)
+	if (cbd == NULL || strlen(lock) != 2)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CLCK=\"%s\",2", lock);
@@ -121,7 +121,7 @@ static void at_call_barring_set(struct ofono_call_barring *cb, const char *lock,
 	char buf[64];
 	int len;
 
-	if (!cbd || strlen(lock) != 2 || (cls && !passwd))
+	if (cbd == NULL || strlen(lock) != 2 || (cls && passwd == NULL))
 		goto error;
 
 	len = snprintf(buf, sizeof(buf), "AT+CLCK=\"%s\",%i", lock, enable);
@@ -164,7 +164,7 @@ static void at_call_barring_set_passwd(struct ofono_call_barring *cb,
 	struct cb_data *cbd = cb_data_new(callback, data);
 	char buf[64];
 
-	if (!cbd || strlen(lock) != 2)
+	if (cbd == NULL || strlen(lock) != 2)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CPWD=\"%s\",\"%s\",\"%s\"",
diff --git a/drivers/atmodem/call-forwarding.c b/drivers/atmodem/call-forwarding.c
index d20ac2e8..a74d4c36 100644
--- a/drivers/atmodem/call-forwarding.c
+++ b/drivers/atmodem/call-forwarding.c
@@ -128,7 +128,7 @@ static void at_ccfc_query(struct ofono_call_forwarding *cf, int type, int cls,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = GINT_TO_POINTER(cls);
@@ -165,7 +165,7 @@ static void at_ccfc_set(struct ofono_call_forwarding *cf, const char *buf,
 	GAtChat *chat = ofono_call_forwarding_get_data(cf);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_at_chat_send(chat, buf, none_prefix,
diff --git a/drivers/atmodem/call-meter.c b/drivers/atmodem/call-meter.c
index 28359afb..5c933971 100644
--- a/drivers/atmodem/call-meter.c
+++ b/drivers/atmodem/call-meter.c
@@ -116,7 +116,7 @@ static void at_caoc_query(struct ofono_call_meter *cm,
 	GAtChat *chat = ofono_call_meter_get_data(cm);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = "+CAOC:";
@@ -137,7 +137,7 @@ static void at_cacm_query(struct ofono_call_meter *cm,
 	GAtChat *chat = ofono_call_meter_get_data(cm);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = "+CACM:";
@@ -169,7 +169,7 @@ static void at_cacm_set(struct ofono_call_meter *cm, const char *passwd,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CACM=\"%s\"", passwd);
@@ -191,7 +191,7 @@ static void at_camm_query(struct ofono_call_meter *cm,
 	GAtChat *chat = ofono_call_meter_get_data(cm);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = "+CAMM:";
@@ -213,7 +213,7 @@ static void at_camm_set(struct ofono_call_meter *cm,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CAMM=\"%06X\",\"%s\"", accmax, passwd);
@@ -274,7 +274,7 @@ static void at_cpuc_query(struct ofono_call_meter *cm,
 	GAtChat *chat = ofono_call_meter_get_data(cm);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = "+CPUC:";
@@ -296,7 +296,7 @@ static void at_cpuc_set(struct ofono_call_meter *cm, const char *currency,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CPUC=\"%s\",\"%f\",\"%s\"",
diff --git a/drivers/atmodem/call-settings.c b/drivers/atmodem/call-settings.c
index b5acc02f..05c94387 100644
--- a/drivers/atmodem/call-settings.c
+++ b/drivers/atmodem/call-settings.c
@@ -84,7 +84,7 @@ static void at_ccwa_query(struct ofono_call_settings *cs, int cls,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = GINT_TO_POINTER(cls);
@@ -122,7 +122,7 @@ static void at_ccwa_set(struct ofono_call_settings *cs, int mode, int cls,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CCWA=1,%d,%d", mode, cls);
@@ -175,7 +175,7 @@ static void at_clip_query(struct ofono_call_settings *cs,
 	GAtChat *chat = ofono_call_settings_get_data(cs);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_at_chat_send(chat, "AT+CLIP?", clip_prefix,
@@ -225,7 +225,7 @@ static void at_colp_query(struct ofono_call_settings *cs,
 	GAtChat *chat = ofono_call_settings_get_data(cs);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_at_chat_send(chat, "AT+COLP?", colp_prefix,
@@ -274,7 +274,7 @@ static void at_clir_query(struct ofono_call_settings *cs,
 	GAtChat *chat = ofono_call_settings_get_data(cs);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_at_chat_send(chat, "AT+CLIR?", clir_prefix,
@@ -305,7 +305,7 @@ static void at_clir_set(struct ofono_call_settings *cs, int mode,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CLIR=%d", mode);
@@ -358,7 +358,7 @@ static void at_colr_query(struct ofono_call_settings *cs,
 	GAtChat *chat = ofono_call_settings_get_data(cs);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_at_chat_send(chat, "AT+COLR", colr_prefix,
diff --git a/drivers/atmodem/call-volume.c b/drivers/atmodem/call-volume.c
index 76d2f96a..fbec6684 100644
--- a/drivers/atmodem/call-volume.c
+++ b/drivers/atmodem/call-volume.c
@@ -138,7 +138,7 @@ static void at_call_volume_speaker_volume(struct ofono_call_volume *cv,
 	char buf[64];
 	int level;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	level = ((cvd->clvl_max - cvd->clvl_min) *
@@ -163,7 +163,7 @@ static void at_call_volume_mute(struct ofono_call_volume *cv, int muted,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CMUT=%d", muted);
diff --git a/drivers/atmodem/cbs.c b/drivers/atmodem/cbs.c
index 2ae75fbd..479bfea6 100644
--- a/drivers/atmodem/cbs.c
+++ b/drivers/atmodem/cbs.c
@@ -74,8 +74,7 @@ static void at_cbm_notify(GAtResult *result, gpointer user_data)
 	}
 
 	hexpdu = g_at_result_pdu(result);
-
-	if (!hexpdu) {
+	if (hexpdu == NULL) {
 		ofono_error("Got a CBM, but no PDU.  Are we in text mode?");
 		return;
 	}
@@ -116,7 +115,7 @@ static void at_cbs_set_topics(struct ofono_cbs *cbs, const char *topics,
 
 	DBG("");
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	/* For the Qualcomm based devices it is required to clear
@@ -155,7 +154,7 @@ static void at_cbs_clear_topics(struct ofono_cbs *cbs,
 
 	DBG("");
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (data->cscb_mode_1)
diff --git a/drivers/atmodem/devinfo.c b/drivers/atmodem/devinfo.c
index 4d3cf983..84ff8988 100644
--- a/drivers/atmodem/devinfo.c
+++ b/drivers/atmodem/devinfo.c
@@ -92,7 +92,7 @@ static void at_query_manufacturer(struct ofono_devinfo *info,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	GAtChat *chat = ofono_devinfo_get_data(info);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = "+CGMI:";
@@ -113,7 +113,7 @@ static void at_query_model(struct ofono_devinfo *info,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	GAtChat *chat = ofono_devinfo_get_data(info);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = "+CGMM:";
@@ -134,7 +134,7 @@ static void at_query_revision(struct ofono_devinfo *info,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	GAtChat *chat = ofono_devinfo_get_data(info);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = "+CGMR:";
@@ -155,7 +155,7 @@ static void at_query_serial(struct ofono_devinfo *info,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	GAtChat *chat = ofono_devinfo_get_data(info);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = "+CGSN:";
diff --git a/drivers/atmodem/gprs-context.c b/drivers/atmodem/gprs-context.c
index 03c6f466..6b657f3f 100644
--- a/drivers/atmodem/gprs-context.c
+++ b/drivers/atmodem/gprs-context.c
@@ -282,7 +282,7 @@ static int at_gprs_context_probe(struct ofono_gprs_context *gc,
 	}
 
 	gcd = g_try_new0(struct gprs_context_data, 1);
-	if (!gcd)
+	if (gcd == NULL)
 		return -ENOMEM;
 
 	gcd->chat = g_at_chat_clone(chat);
diff --git a/drivers/atmodem/gprs.c b/drivers/atmodem/gprs.c
index 94247eca..8cff35b7 100644
--- a/drivers/atmodem/gprs.c
+++ b/drivers/atmodem/gprs.c
@@ -69,7 +69,7 @@ static void at_gprs_set_attached(struct ofono_gprs *gprs, int attached,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CGATT=%i", attached ? 1 : 0);
@@ -115,7 +115,7 @@ static void at_gprs_registration_status(struct ofono_gprs *gprs,
 	struct gprs_data *gd = ofono_gprs_get_data(gprs);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = gd;
@@ -350,7 +350,7 @@ static int at_gprs_probe(struct ofono_gprs *gprs,
 	struct gprs_data *gd;
 
 	gd = g_try_new0(struct gprs_data, 1);
-	if (!gd)
+	if (gd == NULL)
 		return -ENOMEM;
 
 	gd->chat = g_at_chat_clone(chat);
diff --git a/drivers/atmodem/network-registration.c b/drivers/atmodem/network-registration.c
index 5b87b39a..04b0d48c 100644
--- a/drivers/atmodem/network-registration.c
+++ b/drivers/atmodem/network-registration.c
@@ -182,7 +182,7 @@ static void at_registration_status(struct ofono_netreg *netreg,
 	struct netreg_data *nd = ofono_netreg_get_data(netreg);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = nd;
@@ -349,7 +349,7 @@ static void at_current_operator(struct ofono_netreg *netreg,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	gboolean ok;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = netreg;
@@ -408,8 +408,7 @@ static void cops_list_cb(gboolean ok, GAtResult *result, gpointer user_data)
 	DBG("Got %d elements", num);
 
 	list = g_try_new0(struct ofono_network_operator, num);
-
-	if (!list) {
+	if (list == NULL) {
 		CALLBACK_WITH_FAILURE(cb, 0, NULL, cbd->data);
 		return;
 	}
@@ -492,7 +491,7 @@ static void at_list_operators(struct ofono_netreg *netreg,
 	struct netreg_data *nd = ofono_netreg_get_data(netreg);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_at_chat_send(nd->chat, "AT+COPS=?", cops_prefix,
@@ -522,7 +521,7 @@ static void at_register_auto(struct ofono_netreg *netreg,
 	struct netreg_data *nd = ofono_netreg_get_data(netreg);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_at_chat_send(nd->chat, "AT+COPS=0", none_prefix,
@@ -543,7 +542,7 @@ static void at_register_manual(struct ofono_netreg *netreg,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[128];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+COPS=1,2,\"%s%s\"", mcc, mnc);
@@ -564,7 +563,7 @@ static void at_deregister(struct ofono_netreg *netreg,
 	struct netreg_data *nd = ofono_netreg_get_data(netreg);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_at_chat_send(nd->chat, "AT+COPS=2", none_prefix,
@@ -862,7 +861,7 @@ static void at_signal_strength(struct ofono_netreg *netreg,
 	struct netreg_data *nd = ofono_netreg_get_data(netreg);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = nd;
@@ -1045,7 +1044,7 @@ static void creg_notify(GAtResult *result, gpointer user_data)
 	switch (nd->vendor) {
 	case OFONO_VENDOR_OPTION_HSO:
 		tq = g_new0(struct tech_query, 1);
-		if (!tq)
+		if (tq == NULL)
 			break;
 
 		tq->status = status;
diff --git a/drivers/atmodem/phonebook.c b/drivers/atmodem/phonebook.c
index dede2352..731205e5 100644
--- a/drivers/atmodem/phonebook.c
+++ b/drivers/atmodem/phonebook.c
@@ -368,7 +368,7 @@ static void at_export_entries(struct ofono_phonebook *pb, const char *storage,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[32];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = pb;
@@ -536,7 +536,7 @@ static int at_phonebook_probe(struct ofono_phonebook *pb, unsigned int vendor,
 	struct pb_data *pbd;
 
 	pbd = g_try_new0(struct pb_data, 1);
-	if (!pbd)
+	if (pbd == NULL)
 		return -ENOMEM;
 
 	pbd->chat = g_at_chat_clone(chat);
diff --git a/drivers/atmodem/sim-poll.c b/drivers/atmodem/sim-poll.c
index ae1b55c3..daef24a2 100644
--- a/drivers/atmodem/sim-poll.c
+++ b/drivers/atmodem/sim-poll.c
@@ -246,7 +246,7 @@ void atmodem_poll_enable(struct ofono_modem *modem, GAtChat *chat)
 	sim_atom = __ofono_modem_find_atom(modem, OFONO_ATOM_TYPE_SIM);
 	stk_atom = __ofono_modem_find_atom(modem, OFONO_ATOM_TYPE_STK);
 
-	if (!sim_atom)
+	if (sim_atom == NULL)
 		return;
 
 	spd = g_new0(struct sim_poll_data, 1);
diff --git a/drivers/atmodem/sim.c b/drivers/atmodem/sim.c
index 9cfdc650..1653ede7 100644
--- a/drivers/atmodem/sim.c
+++ b/drivers/atmodem/sim.c
@@ -138,7 +138,7 @@ static void at_sim_read_info(struct ofono_sim *sim, int fileid,
 	}
 
 	cbd = cb_data_new(cb, data);
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CRSM=192,%i", fileid);
@@ -211,7 +211,7 @@ static void at_sim_read_binary(struct ofono_sim *sim, int fileid,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CRSM=176,%i,%i,%i,%i", fileid,
@@ -235,7 +235,7 @@ static void at_sim_read_record(struct ofono_sim *sim, int fileid,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CRSM=178,%i,%i,4,%i", fileid,
@@ -300,7 +300,7 @@ static void at_sim_update_binary(struct ofono_sim *sim, int fileid,
 	char *buf = g_try_new(char, 36 + length * 2);
 	int len, ret;
 
-	if (!cbd || !buf)
+	if (cbd == NULL || buf == NULL)
 		goto error;
 
 	len = sprintf(buf, "AT+CRSM=214,%i,%i,%i,%i,", fileid,
@@ -333,7 +333,7 @@ static void at_sim_update_record(struct ofono_sim *sim, int fileid,
 	char *buf = g_try_new(char, 36 + length * 2);
 	int len, ret;
 
-	if (!cbd || !buf)
+	if (cbd == NULL || buf == NULL)
 		goto error;
 
 	len = sprintf(buf, "AT+CRSM=220,%i,%i,4,%i,", fileid,
@@ -365,7 +365,7 @@ static void at_sim_update_cyclic(struct ofono_sim *sim, int fileid,
 	char *buf = g_try_new(char, 36 + length * 2);
 	int len, ret;
 
-	if (!cbd || !buf)
+	if (cbd == NULL || buf == NULL)
 		goto error;
 
 	len = sprintf(buf, "AT+CRSM=220,%i,0,3,%i,", fileid, length);
@@ -421,7 +421,7 @@ static void at_read_imsi(struct ofono_sim *sim, ofono_sim_imsi_cb_t cb,
 	struct sim_data *sd = ofono_sim_get_data(sim);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_at_chat_send(sd->chat, "AT+CIMI", NULL,
@@ -517,7 +517,7 @@ static void at_pin_query(struct ofono_sim *sim, ofono_sim_passwd_cb_t cb,
 	struct sim_data *sd = ofono_sim_get_data(sim);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = sim;
@@ -626,7 +626,7 @@ static void at_pin_send(struct ofono_sim *sim, const char *passwd,
 	char buf[64];
 	int ret;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = sd;
@@ -656,7 +656,7 @@ static void at_pin_send_puk(struct ofono_sim *sim, const char *puk,
 	char buf[64];
 	int ret;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = sd;
@@ -711,10 +711,10 @@ static void at_pin_enable(struct ofono_sim *sim,
 	int ret;
 	unsigned int len = sizeof(at_clck_cpwd_fac) / sizeof(*at_clck_cpwd_fac);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
-	if (passwd_type >= len || !at_clck_cpwd_fac[passwd_type])
+	if (passwd_type >= len || at_clck_cpwd_fac[passwd_type] == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CLCK=\"%s\",%i,\"%s\"",
@@ -745,11 +745,11 @@ static void at_change_passwd(struct ofono_sim *sim,
 	int ret;
 	unsigned int len = sizeof(at_clck_cpwd_fac) / sizeof(*at_clck_cpwd_fac);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (passwd_type >= len ||
-			!at_clck_cpwd_fac[passwd_type])
+			at_clck_cpwd_fac[passwd_type] == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CPWD=\"%s\",\"%s\",\"%s\"",
@@ -808,10 +808,10 @@ static void at_pin_query_enabled(struct ofono_sim *sim,
 	char buf[64];
 	unsigned int len = sizeof(at_clck_cpwd_fac) / sizeof(*at_clck_cpwd_fac);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
-	if (passwd_type >= len || !at_clck_cpwd_fac[passwd_type])
+	if (passwd_type >= len || at_clck_cpwd_fac[passwd_type] == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CLCK=\"%s\",2",
diff --git a/drivers/atmodem/sms.c b/drivers/atmodem/sms.c
index 02cd27a1..559b570f 100644
--- a/drivers/atmodem/sms.c
+++ b/drivers/atmodem/sms.c
@@ -106,7 +106,7 @@ static void at_csca_set(struct ofono_sms *sms,
 	struct cb_data *cbd = cb_data_new(cb, user_data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CSCA=\"%s\",%d", sca->number, sca->type);
@@ -173,7 +173,7 @@ static void at_csca_query(struct ofono_sms *sms, ofono_sms_sca_query_cb_t cb,
 	struct sms_data *data = ofono_sms_get_data(sms);
 	struct cb_data *cbd = cb_data_new(cb, user_data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_at_chat_send(data->chat, "AT+CSCA?", csca_prefix,
@@ -227,7 +227,7 @@ static void at_cmgs(struct ofono_sms *sms, unsigned char *pdu, int pdu_len,
 	char buf[512];
 	int len;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (mms) {
@@ -267,7 +267,7 @@ static void at_cgsms_set(struct ofono_sms *sms, int bearer,
 	struct cb_data *cbd = cb_data_new(cb, user_data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	snprintf(buf, sizeof(buf), "AT+CGSMS=%d", bearer);
@@ -319,7 +319,7 @@ static void at_cgsms_query(struct ofono_sms *sms,
 	struct sms_data *data = ofono_sms_get_data(sms);
 	struct cb_data *cbd = cb_data_new(cb, user_data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_at_chat_send(data->chat, "AT+CGSMS?", cgsms_prefix,
@@ -866,8 +866,7 @@ static void construct_ack_pdu(struct sms_data *d)
 		goto err;
 
 	d->cnma_ack_pdu = encode_hex(pdu, tpdu_len, 0);
-
-	if (!d->cnma_ack_pdu)
+	if (d->cnma_ack_pdu == NULL)
 		goto err;
 
 	d->cnma_ack_pdu_len = tpdu_len;
diff --git a/drivers/atmodem/stk.c b/drivers/atmodem/stk.c
index bd4a7d21..fa8175a6 100644
--- a/drivers/atmodem/stk.c
+++ b/drivers/atmodem/stk.c
@@ -153,7 +153,7 @@ static void at_stk_envelope(struct ofono_stk *stk, int length,
 	char *buf = g_try_new(char, 64 + length * 2);
 	int len, ret;
 
-	if (!cbd || !buf)
+	if (cbd == NULL || buf == NULL)
 		goto error;
 
 	len = sprintf(buf, "AT+CSIM=%i,A0C20000%02hhX",
@@ -236,7 +236,7 @@ static void at_stk_terminal_response(struct ofono_stk *stk, int length,
 	char *buf = g_try_new(char, 64 + length * 2);
 	int len, ret;
 
-	if (!cbd || !buf)
+	if (cbd == NULL || buf == NULL)
 		goto error;
 
 	len = sprintf(buf, "AT+CSIM=%i,A0140000%02hhX",
diff --git a/drivers/atmodem/ussd.c b/drivers/atmodem/ussd.c
index f38dfd04..78f6004d 100644
--- a/drivers/atmodem/ussd.c
+++ b/drivers/atmodem/ussd.c
@@ -187,7 +187,7 @@ static void at_ussd_request(struct ofono_ussd *ussd, int dcs,
 	char buf[512];
 	enum sms_charset charset;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = ussd;
@@ -212,7 +212,7 @@ static void at_ussd_request(struct ofono_ussd *ussd, int dcs,
 		char coded_buf[321];
 		char *converted = encode_hex_own_buf(pdu, len, 0, coded_buf);
 
-		if (!converted)
+		if (converted == NULL)
 			goto error;
 
 		snprintf(buf, sizeof(buf), "AT+CUSD=1,\"%s\",%d",
@@ -264,7 +264,7 @@ static void at_ussd_cancel(struct ofono_ussd *ussd,
 	struct ussd_data *data = ofono_ussd_get_data(ussd);
 	struct cb_data *cbd = cb_data_new(cb, user_data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = data;
diff --git a/drivers/atmodem/voicecall.c b/drivers/atmodem/voicecall.c
index 10b8f4b9..6f2ee9f5 100644
--- a/drivers/atmodem/voicecall.c
+++ b/drivers/atmodem/voicecall.c
@@ -106,7 +106,7 @@ static struct ofono_call *create_call(struct ofono_voicecall *vc, int type,
 
 	/* Generate a call structure for the waiting call */
 	call = g_try_new0(struct ofono_call, 1);
-	if (!call)
+	if (call == NULL)
 		return NULL;
 
 	call->id = ofono_voicecall_get_next_callid(vc);
@@ -154,7 +154,7 @@ static void clcc_poll_cb(gboolean ok, GAtResult *result, gpointer user_data)
 		if (nc && nc->status >= 2 && nc->status <= 5)
 			poll_again = TRUE;
 
-		if (oc && (!nc || (nc->id > oc->id))) {
+		if (oc && (nc == NULL || (nc->id > oc->id))) {
 			enum ofono_disconnect_reason reason;
 
 			if (vd->local_release & (0x1 << oc->id))
@@ -167,7 +167,7 @@ static void clcc_poll_cb(gboolean ok, GAtResult *result, gpointer user_data)
 								reason, NULL);
 
 			o = o->next;
-		} else if (nc && (!oc || (nc->id < oc->id))) {
+		} else if (nc && (oc == NULL || (nc->id < oc->id))) {
 			/* new call, signal it */
 			if (nc->type == 0)
 				ofono_voicecall_notify(vc, nc);
@@ -309,7 +309,7 @@ static void atd_cb(gboolean ok, GAtResult *result, gpointer user_data)
 
 	/* Generate a voice call that was just dialed, we guess the ID */
 	call = create_call(vc, 0, 0, 2, num, type, validity);
-	if (!call) {
+	if (call == NULL) {
 		ofono_error("Unable to malloc, call tracking will fail!");
 		return;
 	}
@@ -339,7 +339,7 @@ static void at_dial(struct ofono_voicecall *vc,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[256];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = vc;
@@ -387,7 +387,7 @@ static void at_template(const char *cmd, struct ofono_voicecall *vc,
 	struct voicecall_data *vd = ofono_voicecall_get_data(vc);
 	struct change_state_req *req = g_try_new0(struct change_state_req, 1);
 
-	if (!req)
+	if (req == NULL)
 		goto error;
 
 	req->vc = vc;
@@ -467,7 +467,7 @@ static void at_release_specific(struct ofono_voicecall *vc, int id,
 	struct release_id_req *req = g_try_new0(struct release_id_req, 1);
 	char buf[32];
 
-	if (!req)
+	if (req == NULL)
 		goto error;
 
 	req->vc = vc;
@@ -571,14 +571,14 @@ static void at_send_dtmf(struct ofono_voicecall *vc, const char *dtmf,
 	int i;
 	char *buf;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = vd;
 
 	/* strlen("+VTS=T;") = 7 + initial AT + null */
 	buf = g_try_new(char, len * 9 + 3);
-	if (!buf)
+	if (buf == NULL)
 		goto error;
 
 	s = sprintf(buf, "AT+VTS=%c", dtmf[0]);
@@ -620,8 +620,7 @@ static void ring_notify(GAtResult *result, gpointer user_data)
 
 	/* Generate an incoming call of unknown type */
 	call = create_call(vc, 9, 1, 4, NULL, 128, 2);
-
-	if (!call) {
+	if (call == NULL) {
 		ofono_error("Couldn't create call, call management is fubar!");
 		return;
 	}
@@ -788,7 +787,7 @@ static void ccwa_notify(GAtResult *result, gpointer user_data)
 
 	call = create_call(vc, class_to_call_type(cls), 1, 5,
 				num, num_type, validity);
-	if (!call) {
+	if (call == NULL) {
 		ofono_error("Unable to malloc. Call management is fubar");
 		return;
 	}
@@ -887,7 +886,7 @@ static int at_voicecall_probe(struct ofono_voicecall *vc, unsigned int vendor,
 	struct voicecall_data *vd;
 
 	vd = g_try_new0(struct voicecall_data, 1);
-	if (!vd)
+	if (vd == NULL)
 		return -ENOMEM;
 
 	vd->chat = g_at_chat_clone(chat);
diff --git a/drivers/calypsomodem/stk.c b/drivers/calypsomodem/stk.c
index 334abc6a..203cb9bc 100644
--- a/drivers/calypsomodem/stk.c
+++ b/drivers/calypsomodem/stk.c
@@ -101,7 +101,7 @@ static void calypso_stk_envelope(struct ofono_stk *stk, int length,
 
 	DBG("");
 
-	if (!cbd || !buf)
+	if (cbd == NULL || buf == NULL)
 		goto error;
 
 	len = sprintf(buf, "AT%%SATE=\"");
@@ -148,7 +148,7 @@ static void calypso_stk_terminal_response(struct ofono_stk *stk, int length,
 
 	DBG("");
 
-	if (!cbd || !buf)
+	if (cbd == NULL || buf == NULL)
 		goto error;
 
 	len = sprintf(buf, "AT%%SATR=\"");
@@ -258,7 +258,7 @@ static int calypso_stk_probe(struct ofono_stk *stk,
 	DBG("");
 
 	sd = g_try_new0(struct stk_data, 1);
-	if (!sd)
+	if (sd == NULL)
 		return -ENOMEM;
 
 	sd->chat = g_at_chat_clone(chat);
diff --git a/drivers/calypsomodem/voicecall.c b/drivers/calypsomodem/voicecall.c
index b2c9a962..0e6a3889 100644
--- a/drivers/calypsomodem/voicecall.c
+++ b/drivers/calypsomodem/voicecall.c
@@ -64,7 +64,7 @@ static void calypso_template(struct ofono_voicecall *vc, const char *cmd,
 	struct voicecall_data *vd = ofono_voicecall_get_data(vc);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_at_chat_send(vd->chat, cmd, none_prefix,
@@ -210,7 +210,7 @@ static void calypso_send_dtmf(struct ofono_voicecall *vc, const char *dtmf,
 	/* strlen("+VTS=\"T\";") = 9 + initial AT + null */
 	buf = g_try_new(char, len * 9 + 3);
 
-	if (!buf) {
+	if (buf == NULL) {
 		CALLBACK_WITH_FAILURE(cb, data);
 		return;
 	}
@@ -390,7 +390,7 @@ static int calypso_voicecall_probe(struct ofono_voicecall *vc,
 	struct voicecall_data *vd;
 
 	vd = g_try_new0(struct voicecall_data, 1);
-	if (!vd)
+	if (vd == NULL)
 		return -ENOMEM;
 
 	vd->chat = g_at_chat_clone(chat);
diff --git a/drivers/hfpmodem/call-volume.c b/drivers/hfpmodem/call-volume.c
index d3807f7c..f985175b 100644
--- a/drivers/hfpmodem/call-volume.c
+++ b/drivers/hfpmodem/call-volume.c
@@ -73,7 +73,7 @@ static void hfp_speaker_volume(struct ofono_call_volume *cv,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	vd->sp_volume = percent;
@@ -100,7 +100,7 @@ static void hfp_microphone_volume(struct ofono_call_volume *cv,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[64];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	vd->mic_volume = percent;
diff --git a/drivers/hfpmodem/network-registration.c b/drivers/hfpmodem/network-registration.c
index 5f123fcf..03ddc7b7 100644
--- a/drivers/hfpmodem/network-registration.c
+++ b/drivers/hfpmodem/network-registration.c
@@ -236,7 +236,7 @@ static void hfp_registration_status(struct ofono_netreg *netreg,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	gboolean ok;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = netreg;
@@ -259,7 +259,7 @@ static void hfp_current_operator(struct ofono_netreg *netreg,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	gboolean ok;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = netreg;
@@ -284,7 +284,7 @@ static void hfp_signal_strength(struct ofono_netreg *netreg,
 	struct netreg_data *nd = ofono_netreg_get_data(netreg);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = netreg;
diff --git a/drivers/hfpmodem/voicecall.c b/drivers/hfpmodem/voicecall.c
index e96ec7c1..53ca4bd5 100644
--- a/drivers/hfpmodem/voicecall.c
+++ b/drivers/hfpmodem/voicecall.c
@@ -80,7 +80,7 @@ static GSList *find_dialing(GSList *calls)
 	c = g_slist_find_custom(calls, GINT_TO_POINTER(CALL_STATUS_DIALING),
 				at_util_call_compare_by_status);
 
-	if (!c)
+	if (c == NULL)
 		c = g_slist_find_custom(calls,
 					GINT_TO_POINTER(CALL_STATUS_ALERTING),
 					at_util_call_compare_by_status);
@@ -97,8 +97,7 @@ static struct ofono_call *create_call(struct ofono_voicecall *vc, int type,
 
 	/* Generate a call structure for the waiting call */
 	call = g_try_new0(struct ofono_call, 1);
-
-	if (!call)
+	if (call == NULL)
 		return NULL;
 
 	call->id = ofono_voicecall_get_next_callid(vc);
@@ -225,7 +224,7 @@ static void clcc_poll_cb(gboolean ok, GAtResult *result, gpointer user_data)
 		if (nc && (nc->status == CALL_STATUS_HELD))
 			num_held++;
 
-		if (oc && (!nc || (nc->id > oc->id))) {
+		if (oc && (nc == NULL || (nc->id > oc->id))) {
 			enum ofono_disconnect_reason reason;
 
 			if (vd->local_release & (0x1 << oc->id))
@@ -240,7 +239,7 @@ static void clcc_poll_cb(gboolean ok, GAtResult *result, gpointer user_data)
 			vd->local_release &= ~(1 << oc->id);
 
 			o = o->next;
-		} else if (nc && (!oc || (nc->id < oc->id))) {
+		} else if (nc && (oc == NULL || (nc->id < oc->id))) {
 			/* new call, signal it */
 			if (nc->type == 0)
 				ofono_voicecall_notify(vc, nc);
@@ -344,8 +343,7 @@ static void atd_cb(gboolean ok, GAtResult *result, gpointer user_data)
 	}
 
 	call = create_call(vc, 0, 0, CALL_STATUS_DIALING, NULL, type, validity);
-
-	if (!call) {
+	if (call == NULL) {
 		ofono_error("Unable to allocate call, "
 				"call tracking will fail!");
 		return;
@@ -364,7 +362,7 @@ static void hfp_dial(struct ofono_voicecall *vc,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[256];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = vc;
@@ -392,7 +390,7 @@ static void hfp_template(const char *cmd, struct ofono_voicecall *vc,
 	struct voicecall_data *vd = ofono_voicecall_get_data(vc);
 	struct change_state_req *req = g_try_new0(struct change_state_req, 1);
 
-	if (!req)
+	if (req == NULL)
 		goto error;
 
 	req->vc = vc;
@@ -506,7 +504,7 @@ static void hfp_release_specific(struct ofono_voicecall *vc, int id,
 
 	req = g_try_new0(struct release_id_req, 1);
 
-	if (!req)
+	if (req == NULL)
 		goto error;
 
 	req->vc = vc;
@@ -584,7 +582,7 @@ static void hfp_send_dtmf(struct ofono_voicecall *vc, const char *dtmf,
 	char *buf;
 	int s;
 
-	if (!req)
+	if (req == NULL)
 		goto error;
 
 	req->vc = vc;
@@ -595,7 +593,7 @@ static void hfp_send_dtmf(struct ofono_voicecall *vc, const char *dtmf,
 	/* strlen("AT+VTS=") = 7 */
 	buf = g_try_new(char, strlen(dtmf) + 7);
 
-	if (!buf)
+	if (buf == NULL)
 		goto error;
 
 	sprintf(buf, "AT+VTS=%s", dtmf);
@@ -654,7 +652,7 @@ static void ccwa_notify(GAtResult *result, gpointer user_data)
 
 	call = create_call(vc, 0, 1, 5, num, num_type, validity);
 
-	if (!call) {
+	if (call == NULL) {
 		ofono_error("malloc call struct failed.  "
 				"Call management is fubar");
 		return;
@@ -725,7 +723,7 @@ static void ring_notify(GAtResult *result, gpointer user_data)
 	/* Generate an incoming call of voice type */
 	call = create_call(vc, 0, 1, CALL_STATUS_INCOMING, NULL, 128, 2);
 
-	if (!call)
+	if (call == NULL)
 		ofono_error("Couldn't create call, call management is fubar!");
 
 	/* We don't know the number must wait for CLIP to arrive before
@@ -878,11 +876,11 @@ static void sync_dialing_cb(gboolean ok, GAtResult *result, gpointer user_data)
 	 */
 	o = find_dialing(vd->calls);
 
-	if (!n && o) {
+	if (n == NULL && o) {
 		oc = o->data;
 		release_call(vc, oc);
 		vd->calls = g_slist_remove(vd->calls, oc);
-	} else if (n && !o) {
+	} else if (n && o == NULL) {
 		nc = n->data;
 		new_call_notify(vc, nc->type, nc->direction, nc->status,
 				nc->phone_number.number, nc->phone_number.type,
diff --git a/drivers/hsomodem/gprs-context.c b/drivers/hsomodem/gprs-context.c
index dc6f1b61..a3f55ab3 100644
--- a/drivers/hsomodem/gprs-context.c
+++ b/drivers/hsomodem/gprs-context.c
@@ -156,7 +156,7 @@ static void hso_gprs_activate_primary(struct ofono_gprs_context *gc,
 	char buf[AUTH_BUF_LENGTH];
 	int len;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	gcd->active_context = ctx->cid;
@@ -200,7 +200,7 @@ static void hso_gprs_deactivate_primary(struct ofono_gprs_context *gc,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[128];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = gc;
diff --git a/drivers/hsomodem/radio-settings.c b/drivers/hsomodem/radio-settings.c
index 3e22065c..70c0efe4 100644
--- a/drivers/hsomodem/radio-settings.c
+++ b/drivers/hsomodem/radio-settings.c
@@ -172,7 +172,7 @@ static int hso_radio_settings_probe(struct ofono_radio_settings *rs,
 	struct radio_settings_data *rsd;
 
 	rsd = g_try_new0(struct radio_settings_data, 1);
-	if (!rsd)
+	if (rsd == NULL)
 		return -ENOMEM;
 
 	rsd->chat = g_at_chat_clone(chat);
diff --git a/drivers/huaweimodem/audio-settings.c b/drivers/huaweimodem/audio-settings.c
index d5d3bba2..305776fb 100644
--- a/drivers/huaweimodem/audio-settings.c
+++ b/drivers/huaweimodem/audio-settings.c
@@ -90,7 +90,7 @@ static int huawei_audio_settings_probe(struct ofono_audio_settings *as,
 	struct audio_settings_data *asd;
 
 	asd = g_try_new0(struct audio_settings_data, 1);
-	if (!asd)
+	if (asd == NULL)
 		return -ENOMEM;
 
 	asd->chat = g_at_chat_clone(chat);
diff --git a/drivers/huaweimodem/gprs-context.c b/drivers/huaweimodem/gprs-context.c
index 48e21ab6..ef3d93c2 100644
--- a/drivers/huaweimodem/gprs-context.c
+++ b/drivers/huaweimodem/gprs-context.c
@@ -311,7 +311,7 @@ static void huawei_gprs_activate_primary(struct ofono_gprs_context *gc,
 
 	DBG("cid %u", ctx->cid);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	gcd->active_context = ctx->cid;
@@ -344,7 +344,7 @@ static void huawei_gprs_deactivate_primary(struct ofono_gprs_context *gc,
 
 	DBG("cid %u", cid);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = gc;
@@ -376,7 +376,7 @@ static int huawei_gprs_context_probe(struct ofono_gprs_context *gc,
 	}
 
 	gcd = g_try_new0(struct gprs_context_data, 1);
-	if (!gcd)
+	if (gcd == NULL)
 		return -ENOMEM;
 
 	gcd->chat = g_at_chat_clone(chat);
diff --git a/drivers/huaweimodem/voicecall.c b/drivers/huaweimodem/voicecall.c
index b4174380..ff08124e 100644
--- a/drivers/huaweimodem/voicecall.c
+++ b/drivers/huaweimodem/voicecall.c
@@ -57,7 +57,7 @@ static struct ofono_call *create_call(struct ofono_voicecall *vc, int type,
 
 	/* Generate a call structure for the waiting call */
 	call = g_try_new0(struct ofono_call, 1);
-	if (!call)
+	if (call == NULL)
 		return NULL;
 
 	call->id = id;
@@ -99,7 +99,7 @@ static void huawei_template(struct ofono_voicecall *vc, const char *cmd,
 	struct voicecall_data *vd = ofono_voicecall_get_data(vc);
 	struct cb_data *cbd = cb_data_new(cb, data);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_at_chat_send(vd->chat, cmd, none_prefix,
@@ -319,7 +319,7 @@ static void orig_notify(GAtResult *result, gpointer user_data)
 	ofono_info("Call origin: id %d type %d", call_id, call_type);
 
 	call = create_call(vc, call_type, 0, 2, NULL, 128, 2, call_id);
-	if (!call) {
+	if (call == NULL) {
 		ofono_error("Unable to malloc, call tracking will fail!");
 		return;
 	}
@@ -472,7 +472,7 @@ static int huawei_voicecall_probe(struct ofono_voicecall *vc,
 	struct voicecall_data *vd;
 
 	vd = g_try_new0(struct voicecall_data, 1);
-	if (!vd)
+	if (vd == NULL)
 		return -ENOMEM;
 
 	vd->chat = g_at_chat_clone(chat);
diff --git a/drivers/ifxmodem/audio-settings.c b/drivers/ifxmodem/audio-settings.c
index fd100aa3..8273335e 100644
--- a/drivers/ifxmodem/audio-settings.c
+++ b/drivers/ifxmodem/audio-settings.c
@@ -116,7 +116,7 @@ static int ifx_audio_settings_probe(struct ofono_audio_settings *as,
 	struct audio_settings_data *asd;
 
 	asd = g_try_new0(struct audio_settings_data, 1);
-	if (!asd)
+	if (asd == NULL)
 		return -ENOMEM;
 
 	asd->chat = g_at_chat_clone(chat);
diff --git a/drivers/ifxmodem/gprs-context.c b/drivers/ifxmodem/gprs-context.c
index 2a2b8df6..fcfe6989 100644
--- a/drivers/ifxmodem/gprs-context.c
+++ b/drivers/ifxmodem/gprs-context.c
@@ -122,7 +122,7 @@ static void failed_setup(struct ofono_gprs_context *gc,
 	gcd->active_context = 0;
 	gcd->state = STATE_IDLE;
 
-	if (!result) {
+	if (result == NULL) {
 		CALLBACK_WITH_FAILURE(gcd->up_cb, NULL, 0, NULL, NULL,
 						NULL, NULL, gcd->cb_data);
 		return;
@@ -154,7 +154,7 @@ static void session_cb(gboolean ok, GAtResult *result, gpointer user_data)
 	dns[2] = 0;
 
 	interface = setup_rawip(gc);
-	if (!interface)
+	if (interface == NULL)
 		interface = "invalid";
 
 	CALLBACK_WITH_SUCCESS(gcd->up_cb, interface, TRUE, gcd->address,
@@ -446,11 +446,11 @@ static int ifx_gprs_context_probe(struct ofono_gprs_context *gc,
 		return -ENODEV;
 	}
 
-	if (!g_at_chat_get_slave(chat))
+	if (g_at_chat_get_slave(chat) == NULL)
 		return -EINVAL;
 
 	gcd = g_try_new0(struct gprs_context_data, 1);
-	if (!gcd)
+	if (gcd == NULL)
 		return -ENOMEM;
 
 	gcd->chat = g_at_chat_clone(chat);
diff --git a/drivers/ifxmodem/radio-settings.c b/drivers/ifxmodem/radio-settings.c
index 89e97e7a..2ec94f15 100644
--- a/drivers/ifxmodem/radio-settings.c
+++ b/drivers/ifxmodem/radio-settings.c
@@ -173,7 +173,7 @@ static int ifx_radio_settings_probe(struct ofono_radio_settings *rs,
 	struct radio_settings_data *rsd;
 
 	rsd = g_try_new0(struct radio_settings_data, 1);
-	if (!rsd)
+	if (rsd == NULL)
 		return -ENOMEM;
 
 	rsd->chat = g_at_chat_clone(chat);
diff --git a/drivers/ifxmodem/stk.c b/drivers/ifxmodem/stk.c
index c17a5ad7..6494c4da 100644
--- a/drivers/ifxmodem/stk.c
+++ b/drivers/ifxmodem/stk.c
@@ -104,7 +104,7 @@ static void ifx_stk_envelope(struct ofono_stk *stk, int length,
 
 	DBG("");
 
-	if (!cbd || !buf)
+	if (cbd == NULL || buf == NULL)
 		goto error;
 
 	len = sprintf(buf, "AT+SATE=\"");
@@ -150,7 +150,7 @@ static void ifx_stk_terminal_response(struct ofono_stk *stk, int length,
 
 	DBG("");
 
-	if (!cbd || !buf)
+	if (cbd == NULL || buf == NULL)
 		goto error;
 
 	len = sprintf(buf, "AT+SATR=\"");
@@ -273,7 +273,7 @@ static int ifx_stk_probe(struct ofono_stk *stk, unsigned int vendor, void *data)
 	DBG("");
 
 	sd = g_try_new0(struct stk_data, 1);
-	if (!sd)
+	if (sd == NULL)
 		return -ENOMEM;
 
 	sd->chat = g_at_chat_clone(chat);
diff --git a/drivers/ifxmodem/voicecall.c b/drivers/ifxmodem/voicecall.c
index 26cc7feb..4bb56816 100644
--- a/drivers/ifxmodem/voicecall.c
+++ b/drivers/ifxmodem/voicecall.c
@@ -94,7 +94,7 @@ static struct ofono_call *create_call(struct ofono_voicecall *vc, int type,
 
 	/* Generate a call structure for the waiting call */
 	call = g_try_new0(struct ofono_call, 1);
-	if (!call)
+	if (call == NULL)
 		return NULL;
 
 	call->id = ofono_voicecall_get_next_callid(vc);
@@ -287,7 +287,7 @@ static void atd_cb(gboolean ok, GAtResult *result, gpointer user_data)
 
 	/* Generate a voice call that was just dialed, we guess the ID */
 	call = create_call(vc, 0, 0, 2, num, type, validity);
-	if (!call) {
+	if (call == NULL) {
 		ofono_error("Unable to malloc, call tracking will fail!");
 		return;
 	}
@@ -311,7 +311,7 @@ static void ifx_dial(struct ofono_voicecall *vc,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[256];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = vc;
@@ -359,7 +359,7 @@ static void ifx_template(const char *cmd, struct ofono_voicecall *vc,
 	struct voicecall_data *vd = ofono_voicecall_get_data(vc);
 	struct change_state_req *req = g_try_new0(struct change_state_req, 1);
 
-	if (!req)
+	if (req == NULL)
 		goto error;
 
 	req->vc = vc;
@@ -431,7 +431,7 @@ static void ifx_release_specific(struct ofono_voicecall *vc, int id,
 	struct release_id_req *req = g_try_new0(struct release_id_req, 1);
 	char buf[32];
 
-	if (!req)
+	if (req == NULL)
 		goto error;
 
 	req->vc = vc;
@@ -518,12 +518,12 @@ static void ifx_send_dtmf(struct ofono_voicecall *vc, const char *dtmf,
 	int i;
 	char *buf;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	/* strlen("+VTS=T\;") = 7 + initial AT + null */
 	buf = g_try_new(char, len * 7 + 3);
-	if (!buf)
+	if (buf == NULL)
 		goto error;
 
 	s = sprintf(buf, "AT+VTS=%c", dtmf[0]);
@@ -689,7 +689,7 @@ static void ccwa_notify(GAtResult *result, gpointer user_data)
 
 	call = create_call(vc, class_to_call_type(cls), 1, 5,
 				num, num_type, validity);
-	if (!call) {
+	if (call == NULL) {
 		ofono_error("Unable to malloc. Call management is fubar");
 		return;
 	}
@@ -723,7 +723,7 @@ static int ifx_voicecall_probe(struct ofono_voicecall *vc, unsigned int vendor,
 	struct voicecall_data *vd;
 
 	vd = g_try_new0(struct voicecall_data, 1);
-	if (!vd)
+	if (vd == NULL)
 		return -ENOMEM;
 
 	vd->chat = g_at_chat_clone(chat);
diff --git a/drivers/isimodem/audio-settings.c b/drivers/isimodem/audio-settings.c
index 80c56488..04774af1 100644
--- a/drivers/isimodem/audio-settings.c
+++ b/drivers/isimodem/audio-settings.c
@@ -107,11 +107,11 @@ static int isi_audio_settings_probe(struct ofono_audio_settings *as,
 	struct audio_settings_data *asd =
 		g_try_new0(struct audio_settings_data, 1);
 
-	if (!asd)
+	if (asd == NULL)
 		return -ENOMEM;
 
 	asd->client = g_isi_client_create(idx, PN_CALL);
-	if (!asd->client) {
+	if (asd->client == NULL) {
 		g_free(asd);
 		return -ENOMEM;
 	}
@@ -128,7 +128,7 @@ static void isi_audio_settings_remove(struct ofono_audio_settings *as)
 {
 	struct audio_settings_data *asd = ofono_audio_settings_get_data(as);
 
-	if (!asd)
+	if (asd == NULL)
 		return;
 
 	ofono_audio_settings_set_data(as, NULL);
diff --git a/drivers/isimodem/call-barring.c b/drivers/isimodem/call-barring.c
index 7cdd218d..5ec9b0c3 100644
--- a/drivers/isimodem/call-barring.c
+++ b/drivers/isimodem/call-barring.c
@@ -128,7 +128,7 @@ static void isi_set(struct ofono_call_barring *barr, const char *lock,
 	DBG("lock code %s enable %d class %d password %s",
 		lock, enable, cls, passwd);
 
-	if (!cbd || !bd)
+	if (cbd == NULL || bd == NULL)
 		goto error;
 
 	if (g_isi_request_make(bd->client, msg, sizeof(msg), SS_TIMEOUT,
@@ -275,7 +275,7 @@ static void isi_query(struct ofono_call_barring *barr, const char *lock,
 
 	DBG("barring query lock code %s", lock);
 
-	if (!cbd || !bd)
+	if (cbd == NULL || bd == NULL)
 		goto error;
 
 	if (g_isi_request_make(bd->client, msg, sizeof(msg), SS_TIMEOUT,
@@ -346,7 +346,7 @@ static void isi_set_passwd(struct ofono_call_barring *barr, const char *lock,
 	DBG("lock code %s (%u) old password %s new password %s",
 		lock, ss_code, old_passwd, new_passwd);
 
-	if (!cbd || !bd)
+	if (cbd == NULL || bd == NULL)
 		goto error;
 
 	if (g_isi_request_make(bd->client, msg, sizeof(msg), SS_TIMEOUT,
@@ -397,11 +397,11 @@ static int isi_call_barring_probe(struct ofono_call_barring *barr,
 	GIsiModem *idx = user;
 	struct barr_data *data = g_try_new0(struct barr_data, 1);
 
-	if (!data)
+	if (data == NULL)
 		return -ENOMEM;
 
 	data->client = g_isi_client_create(idx, PN_SS);
-	if (!data->client)
+	if (data->client == NULL)
 		return -ENOMEM;
 
 	ofono_call_barring_set_data(barr, data);
@@ -415,7 +415,7 @@ static void isi_call_barring_remove(struct ofono_call_barring *barr)
 {
 	struct barr_data *data = ofono_call_barring_get_data(barr);
 
-	if (!data)
+	if (data == NULL)
 		return;
 
 	ofono_call_barring_set_data(barr, NULL);
diff --git a/drivers/isimodem/call-forwarding.c b/drivers/isimodem/call-forwarding.c
index bb25ee7b..e0ec6c28 100644
--- a/drivers/isimodem/call-forwarding.c
+++ b/drivers/isimodem/call-forwarding.c
@@ -229,7 +229,7 @@ static void isi_registration(struct ofono_call_forwarding *cf,
 
 	DBG("forwarding type %d class %d", type, cls);
 
-	if (!cbd || !fd || !number->number || strlen(number->number) > 28)
+	if (cbd == NULL || fd == NULL || !number->number || strlen(number->number) > 28)
 		goto error;
 
 	ss_code = forw_type_to_isi_code(type);
@@ -349,7 +349,7 @@ static void isi_erasure(struct ofono_call_forwarding *cf, int type, int cls,
 
 	DBG("forwarding type %d class %d", type, cls);
 
-	if (!cbd || !fd)
+	if (cbd == NULL || fd == NULL)
 		goto error;
 
 	ss_code = forw_type_to_isi_code(type);
@@ -481,7 +481,7 @@ static void isi_query(struct ofono_call_forwarding *cf, int type, int cls,
 
 	DBG("forwarding type %d class %d", type, cls);
 
-	if (!cbd || !fd || cls != 7)
+	if (cbd == NULL || fd == NULL || cls != 7)
 		goto error;
 
 	ss_code = forw_type_to_isi_code(type);
@@ -540,12 +540,11 @@ static int isi_call_forwarding_probe(struct ofono_call_forwarding *cf,
 	struct forw_data *data;
 
 	data = g_try_new0(struct forw_data, 1);
-
-	if (!data)
+	if (data == NULL)
 		return -ENOMEM;
 
 	data->client = g_isi_client_create(idx, PN_SS);
-	if (!data->client)
+	if (data->client == NULL)
 		return -ENOMEM;
 
 	ofono_call_forwarding_set_data(cf, data);
@@ -560,7 +559,7 @@ static void isi_call_forwarding_remove(struct ofono_call_forwarding *cf)
 {
 	struct forw_data *data = ofono_call_forwarding_get_data(cf);
 
-	if (!data)
+	if (data == NULL)
 		return;
 
 	ofono_call_forwarding_set_data(cf, NULL);
diff --git a/drivers/isimodem/call-meter.c b/drivers/isimodem/call-meter.c
index 336a077e..2fc74c8a 100644
--- a/drivers/isimodem/call-meter.c
+++ b/drivers/isimodem/call-meter.c
@@ -90,11 +90,11 @@ static int isi_call_meter_probe(struct ofono_call_meter *cm,
 	GIsiModem *idx = user;
 	struct call_meter_data *data = g_try_new0(struct call_meter_data, 1);
 
-	if (!data)
+	if (data == NULL)
 		return -ENOMEM;
 
 	data->client = g_isi_client_create(idx, PN_SS);
-	if (!data->client)
+	if (data->client == NULL)
 		return -ENOMEM;
 
 	ofono_call_meter_set_data(cm, data);
diff --git a/drivers/isimodem/call-settings.c b/drivers/isimodem/call-settings.c
index 23c1982b..3f9c07bf 100644
--- a/drivers/isimodem/call-settings.c
+++ b/drivers/isimodem/call-settings.c
@@ -177,7 +177,7 @@ static void isi_cw_query(struct ofono_call_settings *cs, int cls,
 
 	DBG("waiting class %d", cls);
 
-	if (!cbd || !sd)
+	if (cbd == NULL || sd == NULL)
 		goto error;
 
 	if (g_isi_request_make(sd->client, msg, sizeof(msg), SS_TIMEOUT,
@@ -268,7 +268,7 @@ static void isi_cw_set(struct ofono_call_settings *cs, int mode, int cls,
 
 	DBG("waiting mode %d class %d", mode, cls);
 
-	if (!cbd || !sd)
+	if (cbd == NULL || sd == NULL)
 		goto error;
 
 	if (g_isi_request_make(sd->client, msg, sizeof(msg), SS_TIMEOUT,
@@ -320,13 +320,11 @@ static int isi_call_settings_probe(struct ofono_call_settings *cs,
 	struct settings_data *data;
 
 	data = g_try_new0(struct settings_data, 1);
-
-	if (!data)
+	if (data == NULL)
 		return -ENOMEM;
 
 	data->client = g_isi_client_create(idx, PN_SS);
-
-	if (!data->client)
+	if (data->client == NULL)
 		return -ENOMEM;
 
 	ofono_call_settings_set_data(cs, data);
@@ -341,7 +339,7 @@ static void isi_call_settings_remove(struct ofono_call_settings *cs)
 {
 	struct settings_data *data = ofono_call_settings_get_data(cs);
 
-	if (!data)
+	if (data == NULL)
 		return;
 
 	ofono_call_settings_set_data(cs, NULL);
diff --git a/drivers/isimodem/cbs.c b/drivers/isimodem/cbs.c
index 2a327201..f6924ec8 100644
--- a/drivers/isimodem/cbs.c
+++ b/drivers/isimodem/cbs.c
@@ -136,11 +136,11 @@ static int isi_cbs_probe(struct ofono_cbs *cbs, unsigned int vendor,
 		0x00   /* Languages */
 	};
 
-	if (!cd)
+	if (cd == NULL)
 		return -ENOMEM;
 
 	cd->client = g_isi_client_create(idx, PN_SMS);
-	if (!cd->client)
+	if (cd->client == NULL)
 		return -ENOMEM;
 
 	ofono_cbs_set_data(cbs, cd);
@@ -149,8 +149,8 @@ static int isi_cbs_probe(struct ofono_cbs *cbs, unsigned int vendor,
 	if (debug && (strcmp(debug, "all") == 0 || strcmp(debug, "cbs") == 0))
 		g_isi_client_set_debug(cd->client, sms_debug, NULL);
 
-	if (!g_isi_request_make(cd->client, msg, sizeof(msg), CBS_TIMEOUT,
-				routing_resp_cb, cbs))
+	if (g_isi_request_make(cd->client, msg, sizeof(msg), CBS_TIMEOUT,
+				routing_resp_cb, cbs) == NULL)
 		DBG("Failed to set CBS routing.");
 
 	return 0;
@@ -173,7 +173,7 @@ static void isi_cbs_remove(struct ofono_cbs *cbs)
 		0x00   /* Languages */
 	};
 
-	if (!data)
+	if (data == NULL)
 		return;
 
 	if (data->client) {
diff --git a/drivers/isimodem/devinfo.c b/drivers/isimodem/devinfo.c
index f7960ff6..7f94f9e6 100644
--- a/drivers/isimodem/devinfo.c
+++ b/drivers/isimodem/devinfo.c
@@ -128,7 +128,7 @@ static void isi_query_manufacturer(struct ofono_devinfo *info,
 		INFO_PRODUCT_MANUFACTURER
 	};
 
-	if (!cbd || !dev)
+	if (cbd == NULL || dev == NULL)
 		goto error;
 
 	if (g_isi_request_make(dev->client, msg, sizeof(msg),
@@ -152,7 +152,7 @@ static void isi_query_model(struct ofono_devinfo *info,
 		INFO_PRODUCT_NAME
 	};
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_isi_request_make(dev->client, msg, sizeof(msg),
@@ -177,7 +177,7 @@ static void isi_query_revision(struct ofono_devinfo *info,
 		0x00, 0x00, 0x00, 0x00
 	};
 
-	if (!cbd || !dev)
+	if (cbd == NULL || dev == NULL)
 		goto error;
 
 	if (g_isi_request_make(dev->client, msg, sizeof(msg),
@@ -201,7 +201,7 @@ static void isi_query_serial(struct ofono_devinfo *info,
 		INFO_SN_IMEI_PLAIN
 	};
 
-	if (!cbd || !dev)
+	if (cbd == NULL || dev == NULL)
 		goto error;
 
 	if (g_isi_request_make(dev->client, msg, sizeof(msg),
@@ -252,11 +252,11 @@ static int isi_devinfo_probe(struct ofono_devinfo *info, unsigned int vendor,
 	GIsiModem *idx = user;
 	struct devinfo_data *data = g_try_new0(struct devinfo_data, 1);
 
-	if (!data)
+	if (data == NULL)
 		return -ENOMEM;
 
 	data->client = g_isi_client_create(idx, PN_PHONE_INFO);
-	if (!data->client) {
+	if (data->client == NULL) {
 		g_free(data);
 		return -ENOMEM;
 	}
diff --git a/drivers/isimodem/gprs-context.c b/drivers/isimodem/gprs-context.c
index 88450b8a..2dc1263d 100644
--- a/drivers/isimodem/gprs-context.c
+++ b/drivers/isimodem/gprs-context.c
@@ -85,7 +85,7 @@ struct context_data {
 
 static void reset_context(struct context_data *cd)
 {
-	if (!cd)
+	if (cd == NULL)
 		return;
 
 	g_isi_remove_subscription(cd->client, PN_GPDS,
@@ -399,8 +399,8 @@ static void send_context_authenticate(GIsiClient *client, void *opaque)
 		{ cd->password, password_len },
 	};
 
-	if (!g_isi_request_vmake(client, iov, 4, GPDS_TIMEOUT,
-					context_auth_cb, cd))
+	if (g_isi_request_vmake(client, iov, 4, GPDS_TIMEOUT,
+					context_auth_cb, cd) == NULL)
 		gprs_up_fail(cd);
 }
 
@@ -478,8 +478,8 @@ static gboolean create_context_cb(GIsiClient *client,
 
 	cd->handle = msg[1] = resp[1];
 
-	if (!g_isi_request_make(client, msg, sizeof(msg), GPDS_TIMEOUT,
-				link_conf_cb, cd))
+	if (g_isi_request_make(client, msg, sizeof(msg), GPDS_TIMEOUT,
+						link_conf_cb, cd) == NULL)
 		return gprs_up_fail(cd);
 
 	/* TODO: send context configuration at the same time? */
@@ -495,8 +495,8 @@ static void create_pipe_cb(GIsiPipe *pipe)
 		GPDS_CONTEXT_ID_CREATE_REQ,
 	};
 
-	if (!g_isi_request_make(cd->client, msg, sizeof(msg), GPDS_TIMEOUT,
-				create_context_cb, cd))
+	if (g_isi_request_make(cd->client, msg, sizeof(msg), GPDS_TIMEOUT,
+					create_context_cb, cd) == NULL)
 		gprs_up_fail(cd);
 }
 
@@ -582,7 +582,7 @@ static void isi_gprs_deactivate_primary(struct ofono_gprs_context *gc,
 		0x00,	/* GPDS context ID, added later */
 	};
 
-	if (!cd)
+	if (cd == NULL)
 		return;
 
 	cd->down_cb = cb;
@@ -590,8 +590,8 @@ static void isi_gprs_deactivate_primary(struct ofono_gprs_context *gc,
 
 	msg[1] = cd->handle;
 
-	if (!g_isi_request_make(cd->client, msg, sizeof(msg), GPDS_TIMEOUT,
-					context_deactivate_cb, cd)) {
+	if (g_isi_request_make(cd->client, msg, sizeof(msg), GPDS_TIMEOUT,
+					context_deactivate_cb, cd) == NULL) {
 		gprs_down_fail(cd);
 		return;
 	}
@@ -630,11 +630,11 @@ static int isi_gprs_context_probe(struct ofono_gprs_context *gc,
 	GIsiModem *idx = user;
 	struct context_data *cd = g_try_new0(struct context_data, 1);
 
-	if (!cd)
+	if (cd == NULL)
 		return -ENOMEM;
 
 	cd->client = g_isi_client_create(idx, PN_GPDS);
-	if (!cd->client) {
+	if (cd->client == NULL) {
 		g_free(cd);
 		return -ENOMEM;
 	}
@@ -652,7 +652,7 @@ static void isi_gprs_context_remove(struct ofono_gprs_context *gc)
 {
 	struct context_data *cd = ofono_gprs_context_get_data(gc);
 
-	if (!cd)
+	if (cd == NULL)
 		return;
 
 	ofono_gprs_context_set_data(gc, NULL);
diff --git a/drivers/isimodem/gprs.c b/drivers/isimodem/gprs.c
index 9cbe4f3b..3c9facde 100644
--- a/drivers/isimodem/gprs.c
+++ b/drivers/isimodem/gprs.c
@@ -165,11 +165,11 @@ static int isi_gprs_probe(struct ofono_gprs *gprs,
 	GIsiModem *idx = user;
 	struct gprs_data *gd = g_try_new0(struct gprs_data, 1);
 
-	if (!gd)
+	if (gd == NULL)
 		return -ENOMEM;
 
 	gd->client = g_isi_client_create(idx, PN_GPDS);
-	if (!gd->client) {
+	if (gd->client == NULL) {
 		g_free(gd);
 		return -ENOMEM;
 	}
@@ -187,7 +187,7 @@ static void isi_gprs_remove(struct ofono_gprs *gprs)
 {
 	struct gprs_data *data = ofono_gprs_get_data(gprs);
 
-	if (!data)
+	if (data == NULL)
 		return;
 
 	ofono_gprs_set_data(gprs, NULL);
@@ -286,7 +286,7 @@ static void isi_gprs_set_attached(struct ofono_gprs *gprs, int attached,
 
 	GIsiRequest *req;
 
-	if (!cbd || !gd)
+	if (cbd == NULL || gd == NULL)
 		goto error;
 
 	if (attached)
@@ -356,7 +356,7 @@ static void isi_gprs_attached_status(struct ofono_gprs *gprs,
 		GPDS_STATUS_REQ,
 	};
 
-	if (!cbd || !gd)
+	if (cbd == NULL || gd == NULL)
 		goto error;
 
 	if (g_isi_send(gd->client, msg, sizeof(msg), GPDS_TIMEOUT,
diff --git a/drivers/isimodem/infoserver.c b/drivers/isimodem/infoserver.c
index 7f07da31..96659964 100644
--- a/drivers/isimodem/infoserver.c
+++ b/drivers/isimodem/infoserver.c
@@ -93,11 +93,11 @@ struct isi_infoserver *isi_infoserver_create(struct ofono_modem *modem,
 	struct isi_infoserver *self;
 
 	self = g_new0(struct isi_infoserver, 1);
-	if (!self)
+	if (self == NULL)
 		return NULL;
 
 	self->server = g_isi_server_create(data, PN_EPOC_INFO, 0, 0);
-	if (!self->server) {
+	if (self->server == NULL) {
 		g_free(self);
 		return NULL;
 	}
diff --git a/drivers/isimodem/network-registration.c b/drivers/isimodem/network-registration.c
index 1e7c8927..44e84240 100644
--- a/drivers/isimodem/network-registration.c
+++ b/drivers/isimodem/network-registration.c
@@ -255,7 +255,7 @@ static void isi_registration_status(struct ofono_netreg *netreg,
 		NET_REG_STATUS_GET_REQ
 	};
 
-	if (!cbd || !nd)
+	if (cbd == NULL || nd == NULL)
 		goto error;
 
 	if (g_isi_request_make(nd->client, msg, sizeof(msg),
@@ -360,7 +360,7 @@ static void isi_current_operator(struct ofono_netreg *netreg,
 		0x00  /* No sub-blocks */
 	};
 
-	if (!cbd || !nd)
+	if (cbd == NULL || nd == NULL)
 		goto error;
 
 	if (g_isi_request_make(nd->client, msg, sizeof(msg),
@@ -482,7 +482,7 @@ static void isi_list_operators(struct ofono_netreg *netreg,
 		0x00
 	};
 
-	if (!cbd || !net)
+	if (cbd == NULL || net == NULL)
 		goto error;
 
 	if (g_isi_request_make(net->client, msg, sizeof(msg),
@@ -548,7 +548,7 @@ static void isi_register_auto(struct ofono_netreg *netreg,
 		0x00  /* Index not used */
 	};
 
-	if (!cbd || !net)
+	if (cbd == NULL || net == NULL)
 		goto error;
 
 	if (g_isi_request_make(net->client, msg, sizeof(msg),
@@ -621,7 +621,7 @@ static void isi_register_manual(struct ofono_netreg *netreg,
 		0x00, 0x00  /* Filler */
 	};
 
-	if (!cbd || !nd)
+	if (cbd == NULL || nd == NULL)
 		goto error;
 
 	if (g_isi_request_make(nd->client, msg, sizeof(msg),
@@ -866,7 +866,7 @@ static void isi_strength(struct ofono_netreg *netreg,
 		NET_CURRENT_CELL_RSSI
 	};
 
-	if (!cbd || !nd)
+	if (cbd == NULL || nd == NULL)
 		goto error;
 
 	if (g_isi_request_make(nd->client, msg, sizeof(msg),
@@ -901,9 +901,8 @@ static gboolean isi_netreg_register(gpointer user)
 	g_isi_subscribe(nd->client, NET_TIME_IND, time_ind_cb, netreg);
 
 	/* Bootstrap current RAT setting */
-	if (!g_isi_request_make(nd->client, rat, sizeof(rat),
-				NETWORK_TIMEOUT,
-				rat_resp_cb, netreg))
+	if (g_isi_request_make(nd->client, rat, sizeof(rat),
+				NETWORK_TIMEOUT, rat_resp_cb, netreg) == NULL)
 		DBG("Failed to bootstrap RAT");
 
 	ofono_netreg_register(netreg);
@@ -935,11 +934,11 @@ static int isi_netreg_probe(struct ofono_netreg *netreg, unsigned int vendor,
 	GIsiModem *idx = user;
 	struct netreg_data *nd = g_try_new0(struct netreg_data, 1);
 
-	if (!nd)
+	if (nd == NULL)
 		return -ENOMEM;
 
 	nd->client = g_isi_client_create(idx, PN_NETWORK);
-	if (!nd->client) {
+	if (nd->client == NULL) {
 		g_free(nd);
 		return -ENOMEM;
 	}
@@ -954,7 +953,7 @@ static void isi_netreg_remove(struct ofono_netreg *net)
 {
 	struct netreg_data *data = ofono_netreg_get_data(net);
 
-	if (!data)
+	if (data == NULL)
 		return;
 
 	ofono_netreg_set_data(net, NULL);
diff --git a/drivers/isimodem/phonebook.c b/drivers/isimodem/phonebook.c
index dc832c44..5ee43152 100644
--- a/drivers/isimodem/phonebook.c
+++ b/drivers/isimodem/phonebook.c
@@ -192,7 +192,7 @@ static void read_next_entry(GIsiClient *client, int location,
 	if (location < 0)
 		goto error;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	if (g_isi_request_make(client, msg, sizeof(msg), SIM_TIMEOUT,
@@ -259,7 +259,7 @@ static void isi_export_entries(struct ofono_phonebook *pb, const char *storage,
 		0, 0				/* filler */
 	};
 
-	if (!cbd || !pbd)
+	if (cbd == NULL || pbd == NULL)
 		goto error;
 
 	if (strcmp(storage, "SM"))
@@ -314,11 +314,11 @@ static int isi_phonebook_probe(struct ofono_phonebook *pb, unsigned int vendor,
 	GIsiModem *idx = user;
 	struct pb_data *data = g_try_new0(struct pb_data, 1);
 
-	if (!data)
+	if (data == NULL)
 		return -ENOMEM;
 
 	data->client = g_isi_client_create(idx, PN_SIM);
-	if (!data->client) {
+	if (data->client == NULL) {
 		g_free(data);
 		return -ENOMEM;
 	}
@@ -335,7 +335,7 @@ static void isi_phonebook_remove(struct ofono_phonebook *pb)
 {
 	struct pb_data *data = ofono_phonebook_get_data(pb);
 
-	if (!data)
+	if (data == NULL)
 		return;
 
 	ofono_phonebook_set_data(pb, NULL);
diff --git a/drivers/isimodem/radio-settings.c b/drivers/isimodem/radio-settings.c
index 6111b3ad..01c67195 100644
--- a/drivers/isimodem/radio-settings.c
+++ b/drivers/isimodem/radio-settings.c
@@ -159,7 +159,7 @@ static void isi_query_rat_mode(struct ofono_radio_settings *rs,
 		0x00 /* subblock count */
 	};
 
-	if (!cbd || !rd)
+	if (cbd == NULL || rd == NULL)
 		goto error;
 
 	if (g_isi_request_make(rd->client, msg, sizeof(msg), GSS_TIMEOUT,
@@ -226,7 +226,7 @@ static void isi_set_rat_mode(struct ofono_radio_settings *rs,
 		0x00 /* filler */
 	};
 
-	if (!cbd || !rd)
+	if (cbd == NULL || rd == NULL)
 		goto error;
 
 	if (isi_mode == -1)
@@ -363,11 +363,11 @@ static int isi_radio_settings_probe(struct ofono_radio_settings *rs,
 	GIsiModem *idx = user;
 	struct radio_data *rd = g_try_new0(struct radio_data, 1);
 
-	if (!rd)
+	if (rd == NULL)
 		return -ENOMEM;
 
 	rd->client = g_isi_client_create(idx, PN_GSS);
-	if (!rd->client) {
+	if (rd->client == NULL) {
 		g_free(rd);
 		return -ENOMEM;
 	}
@@ -384,7 +384,7 @@ static void isi_radio_settings_remove(struct ofono_radio_settings *rs)
 {
 	struct radio_data *rd = ofono_radio_settings_get_data(rs);
 
-	if (!rd)
+	if (rd == NULL)
 		return;
 
 	ofono_radio_settings_set_data(rs, NULL);
diff --git a/drivers/isimodem/sim.c b/drivers/isimodem/sim.c
index d03a07e9..b79c52af 100644
--- a/drivers/isimodem/sim.c
+++ b/drivers/isimodem/sim.c
@@ -156,7 +156,7 @@ static gboolean isi_read_spn(struct ofono_sim *sim, struct isi_cb_data *cbd)
 		0
 	};
 
-	if (!sd)
+	if (sd == NULL)
 		return FALSE;
 
 	return g_isi_request_make(sd->client, msg, sizeof(msg),
@@ -200,7 +200,7 @@ static gboolean isi_read_iccid(struct ofono_sim *sim, struct isi_cb_data *cbd)
 	struct sim_data *sd = ofono_sim_get_data(sim);
 	const unsigned char req[] = { SIM_READ_FIELD_REQ, ICC };
 
-	if (!sd)
+	if (sd == NULL)
 		return FALSE;
 
 	return g_isi_request_make(sd->client, req, sizeof(req), SIM_TIMEOUT,
@@ -343,7 +343,7 @@ static void isi_read_imsi(struct ofono_sim *sim,
 		READ_IMSI
 	};
 
-	if (!cbd || !sd)
+	if (cbd == NULL || sd == NULL)
 		goto error;
 
 	if (g_isi_request_make(sd->client, msg, sizeof(msg), SIM_TIMEOUT,
@@ -451,11 +451,11 @@ static int isi_sim_probe(struct ofono_sim *sim, unsigned int vendor,
 	struct sim_data *sd = g_try_new0(struct sim_data, 1);
 	const char *debug = getenv("OFONO_ISI_DEBUG");
 
-	if (!sd)
+	if (sd == NULL)
 		return -ENOMEM;
 
 	sd->client = g_isi_client_create(idx, PN_SIM);
-	if (!sd->client)
+	if (sd->client == NULL)
 		return -ENOMEM;
 
 	ofono_sim_set_data(sim, sd);
@@ -472,7 +472,7 @@ static void isi_sim_remove(struct ofono_sim *sim)
 {
 	struct sim_data *data = ofono_sim_get_data(sim);
 
-	if (!data)
+	if (data == NULL)
 		return;
 
 	ofono_sim_set_data(sim, NULL);
diff --git a/drivers/isimodem/sms.c b/drivers/isimodem/sms.c
index e2c2533d..e8527dd8 100644
--- a/drivers/isimodem/sms.c
+++ b/drivers/isimodem/sms.c
@@ -156,7 +156,7 @@ static void isi_sca_query(struct ofono_sms *sms,
 		1,	/* Location, default is 1 */
 	};
 
-	if (!cbd || !sd)
+	if (cbd == NULL || sd == NULL)
 		goto error;
 
 	if (g_isi_send(sd->sim, msg, sizeof(msg), SIM_TIMEOUT,
@@ -214,7 +214,7 @@ static void isi_sca_set(struct ofono_sms *sms,
 		{ &sd->params, sizeof(sd->params) },
 	};
 
-	if (!cbd || !sd)
+	if (cbd == NULL || sd == NULL)
 		goto error;
 
 	bcd = sd->params.sca;
@@ -350,7 +350,7 @@ static void isi_submit(struct ofono_sms *sms, unsigned char *pdu,
 		{ sca_sb, sca_sb_len },
 	};
 
-	if (!cbd || !sd)
+	if (cbd == NULL || sd == NULL)
 		goto error;
 
 	if (use_sca) {
@@ -560,18 +560,18 @@ static int isi_sms_probe(struct ofono_sms *sms, unsigned int vendor,
 		0x00  /* Sub-sub-block count */
 	};
 
-	if (!data)
+	if (data == NULL)
 		return -ENOMEM;
 
 	data->params.absent = 0xff;
 	data->params.alphalen = 1; /* Includes final UCS2-coded NUL */
 
 	data->client = g_isi_client_create(idx, PN_SMS);
-	if (!data->client)
+	if (data->client == NULL)
 		return -ENOMEM;
 
 	data->sim = g_isi_client_create(idx, PN_SIM);
-	if (!data->sim) {
+	if (data->sim == NULL) {
 		g_isi_client_destroy(data->client);
 		return -ENOMEM;
 	}
@@ -586,8 +586,8 @@ static int isi_sms_probe(struct ofono_sms *sms, unsigned int vendor,
 
 	g_isi_subscribe(data->client, SMS_MESSAGE_SEND_STATUS_IND,
 			send_status_ind_cb, sms);
-	if (!g_isi_send(data->client, msg, sizeof(msg), SMS_TIMEOUT,
-			routing_resp_cb, sms, NULL))
+	if (g_isi_send(data->client, msg, sizeof(msg), SMS_TIMEOUT,
+					routing_resp_cb, sms, NULL) == NULL)
 		DBG("Failed to set SMS routing.");
 
 	return 0;
@@ -609,7 +609,7 @@ static void isi_sms_remove(struct ofono_sms *sms)
 		0x00  /* Sub-sub-block count */
 	};
 
-	if (!data)
+	if (data == NULL)
 		return;
 
 	ofono_sms_set_data(sms, NULL);
diff --git a/drivers/isimodem/ssn.c b/drivers/isimodem/ssn.c
index 797ba9d2..402a48a5 100644
--- a/drivers/isimodem/ssn.c
+++ b/drivers/isimodem/ssn.c
@@ -51,11 +51,11 @@ static int isi_ssn_probe(struct ofono_ssn *ssn, unsigned int vendor,
 	GIsiModem *idx = user;
 	struct ssn_data *data = g_try_new0(struct ssn_data, 1);
 
-	if (!data)
+	if (data == NULL)
 		return -ENOMEM;
 
 	data->client = g_isi_client_create(idx, PN_SS);
-	if (!data->client)
+	if (data->client == NULL)
 		return -ENOMEM;
 
 	ofono_ssn_set_data(ssn, data);
@@ -67,7 +67,7 @@ static void isi_ssn_remove(struct ofono_ssn *ssn)
 {
 	struct ssn_data *data = ofono_ssn_get_data(ssn);
 
-	if (!data)
+	if (data == NULL)
 		return;
 
 	ofono_ssn_set_data(ssn, NULL);
diff --git a/drivers/isimodem/ussd.c b/drivers/isimodem/ussd.c
index 78ac9fe7..a509a0ae 100644
--- a/drivers/isimodem/ussd.c
+++ b/drivers/isimodem/ussd.c
@@ -181,7 +181,7 @@ static void isi_request(struct ofono_ussd *ussd, int dcs,
 		{ (uint8_t *)pdu, len }
 	};
 
-	if (!cbd || !ud)
+	if (cbd == NULL || ud == NULL)
 		goto error;
 
 	if (g_isi_vsend(ud->client, iov, 2, SS_TIMEOUT,
@@ -205,7 +205,7 @@ static void isi_cancel(struct ofono_ussd *ussd,
 		0x00		/* subblock count */
 	};
 
-	if (!cbd || !ud)
+	if (cbd == NULL || ud == NULL)
 		goto error;
 
 	if (g_isi_send(ud->client, msg, sizeof(msg), SS_TIMEOUT,
@@ -258,11 +258,11 @@ static int isi_ussd_probe(struct ofono_ussd *ussd, unsigned int vendor,
 	GIsiModem *idx = user;
 	struct ussd_data *ud = g_try_new0(struct ussd_data, 1);
 
-	if (!ud)
+	if (ud == NULL)
 		return -ENOMEM;
 
 	ud->client = g_isi_client_create(idx, PN_SS);
-	if (!ud->client)
+	if (ud->client == NULL)
 		return -ENOMEM;
 
 	ofono_ussd_set_data(ussd, ud);
@@ -275,7 +275,7 @@ static void isi_ussd_remove(struct ofono_ussd *ussd)
 {
 	struct ussd_data *data = ofono_ussd_get_data(ussd);
 
-	if (!data)
+	if (data == NULL)
 		return;
 
 	ofono_ussd_set_data(ussd, NULL);
diff --git a/drivers/isimodem/voicecall.c b/drivers/isimodem/voicecall.c
index 497a2ce0..84b77d16 100644
--- a/drivers/isimodem/voicecall.c
+++ b/drivers/isimodem/voicecall.c
@@ -176,7 +176,7 @@ static gboolean isi_ctx_return(struct isi_call_req_context *irc,
 				enum ofono_error_type type,
 				int error)
 {
-	if (!irc)
+	if (irc == NULL)
 		return TRUE;
 
 	if (irc->cb) {
@@ -1252,14 +1252,14 @@ static int isi_voicecall_probe(struct ofono_voicecall *ovc,
 	struct isi_voicecall *ivc = g_try_new0(struct isi_voicecall, 1);
 	int id;
 
-	if (!ivc)
+	if (ivc == NULL)
 		return -ENOMEM;
 
 	for (id = 0; id <= 7; id++)
 		ivc->calls[id].id = id;
 
 	ivc->client = g_isi_client_create(idx, PN_CALL);
-	if (!ivc->client) {
+	if (ivc->client == NULL) {
 		g_free(ivc);
 		return -ENOMEM;
 	}
@@ -1302,9 +1302,9 @@ static gboolean isi_call_register(gpointer _ovc)
 			CALL_STATUS_IND, isi_call_status_ind_cb,
 			ovc);
 
-	if (!isi_call_status_req(ovc, CALL_ID_ALL,
-					CALL_STATUS_MODE_ADDR_AND_ORIGIN,
-					NULL, NULL))
+	if (isi_call_status_req(ovc, CALL_ID_ALL,
+				CALL_STATUS_MODE_ADDR_AND_ORIGIN,
+				NULL, NULL) == NULL)
 		DBG("Failed to request call status");
 
 	ofono_voicecall_register(ovc);
@@ -1316,7 +1316,7 @@ static void isi_voicecall_remove(struct ofono_voicecall *call)
 {
 	struct isi_voicecall *data = ofono_voicecall_get_data(call);
 
-	if (!data)
+	if (data == NULL)
 		return;
 
 	ofono_voicecall_set_data(call, NULL);
diff --git a/drivers/mbmmodem/gprs-context.c b/drivers/mbmmodem/gprs-context.c
index 553b7fd1..0a1ca2c3 100644
--- a/drivers/mbmmodem/gprs-context.c
+++ b/drivers/mbmmodem/gprs-context.c
@@ -364,7 +364,7 @@ static void mbm_gprs_activate_primary(struct ofono_gprs_context *gc,
 
 	DBG("cid %u", ctx->cid);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	gcd->active_context = ctx->cid;
@@ -408,7 +408,7 @@ static void mbm_gprs_deactivate_primary(struct ofono_gprs_context *gc,
 
 	DBG("cid %u", cid);
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = gc;
@@ -471,7 +471,7 @@ static int mbm_gprs_context_probe(struct ofono_gprs_context *gc,
 	DBG("");
 
 	gcd = g_try_new0(struct gprs_context_data, 1);
-	if (!gcd)
+	if (gcd == NULL)
 		return -ENOMEM;
 
 	gcd->chat = g_at_chat_clone(chat);
diff --git a/drivers/mbmmodem/stk.c b/drivers/mbmmodem/stk.c
index 87a2dd0e..81c36dba 100644
--- a/drivers/mbmmodem/stk.c
+++ b/drivers/mbmmodem/stk.c
@@ -88,7 +88,7 @@ static void mbm_stk_envelope(struct ofono_stk *stk, int length,
 
 	DBG("");
 
-	if (!cbd || !buf)
+	if (cbd == NULL || buf == NULL)
 		goto error;
 
 	len = sprintf(buf, "AT*STKE=\"");
@@ -134,7 +134,7 @@ static void mbm_stk_terminal_response(struct ofono_stk *stk, int length,
 
 	DBG("");
 
-	if (!cbd || !buf)
+	if (cbd == NULL || buf == NULL)
 		goto error;
 
 	len = sprintf(buf, "AT*STKR=\"");
@@ -236,7 +236,7 @@ static int mbm_stk_probe(struct ofono_stk *stk, unsigned int vendor, void *data)
 	DBG("");
 
 	sd = g_try_new0(struct stk_data, 1);
-	if (!sd)
+	if (sd == NULL)
 		return -ENOMEM;
 
 	sd->chat = g_at_chat_clone(chat);
diff --git a/drivers/nwmodem/radio-settings.c b/drivers/nwmodem/radio-settings.c
index 2f5527e1..36fab393 100644
--- a/drivers/nwmodem/radio-settings.c
+++ b/drivers/nwmodem/radio-settings.c
@@ -170,7 +170,7 @@ static int nw_radio_settings_probe(struct ofono_radio_settings *rs,
 	struct radio_settings_data *rsd;
 
 	rsd = g_try_new0(struct radio_settings_data, 1);
-	if (!rsd)
+	if (rsd == NULL)
 		return -ENOMEM;
 
 	rsd->chat = g_at_chat_clone(chat);
diff --git a/drivers/stemodem/gprs-context.c b/drivers/stemodem/gprs-context.c
index 1675cd8d..faa31241 100644
--- a/drivers/stemodem/gprs-context.c
+++ b/drivers/stemodem/gprs-context.c
@@ -158,7 +158,7 @@ static struct conn_info *conn_info_create(unsigned int device,
 {
 	struct conn_info *connection = g_try_new0(struct conn_info, 1);
 
-	if (!connection)
+	if (connection == NULL)
 		return NULL;
 
 	connection->cid = 0;
@@ -206,7 +206,7 @@ static void ste_eppsd_down_cb(gboolean ok, GAtResult *result,
 				GUINT_TO_POINTER(gcd->active_context),
 				conn_compare_by_cid);
 
-	if (!l) {
+	if (l == NULL) {
 		DBG("Did not find data (used caif device) for"
 					"connection with cid; %d",
 					gcd->active_context);
@@ -247,7 +247,7 @@ static void ste_eppsd_up_cb(gboolean ok, GAtResult *result, gpointer user_data)
 				GUINT_TO_POINTER(gcd->active_context),
 				conn_compare_by_cid);
 
-	if (!l) {
+	if (l == NULL) {
 		DBG("Did not find data (device and channel id)"
 					"for connection with cid; %d",
 					gcd->active_context);
@@ -344,7 +344,7 @@ static void ste_cgdcont_cb(gboolean ok, GAtResult *result, gpointer user_data)
 	l = g_slist_find_custom(g_caif_devices, GUINT_TO_POINTER(0),
 				conn_compare_by_cid);
 
-	if (!l) {
+	if (l == NULL) {
 		DBG("at_cgdcont_cb, no more available devices");
 		goto error;
 	}
@@ -376,7 +376,7 @@ static void ste_gprs_activate_primary(struct ofono_gprs_context *gc,
 	char buf[AUTH_BUF_LENGTH];
 	int len;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	gcd->active_context = ctx->cid;
@@ -421,7 +421,7 @@ static void ste_gprs_deactivate_primary(struct ofono_gprs_context *gc,
 	char buf[64];
 	GSList *l;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	gcd->active_context = id;
@@ -430,7 +430,7 @@ static void ste_gprs_deactivate_primary(struct ofono_gprs_context *gc,
 	l = g_slist_find_custom(g_caif_devices, GUINT_TO_POINTER(id),
 				conn_compare_by_cid);
 
-	if (!l) {
+	if (l == NULL) {
 		DBG("at_gprs_deactivate_primary, did not find"
 			"data (channel id) for connection with cid; %d", id);
 		goto error;
diff --git a/drivers/stemodem/radio-settings.c b/drivers/stemodem/radio-settings.c
index 5b16ec0b..e65baf46 100644
--- a/drivers/stemodem/radio-settings.c
+++ b/drivers/stemodem/radio-settings.c
@@ -192,8 +192,9 @@ static int ste_radio_settings_probe(struct ofono_radio_settings *rs,
 {
 	GAtChat *chat = data;
 	struct radio_settings_data *rsd;
+
 	rsd = g_try_new0(struct radio_settings_data, 1);
-	if (!rsd)
+	if (rsd == NULL)
 		return -ENOMEM;
 
 	rsd->chat = chat;
diff --git a/drivers/stemodem/voicecall.c b/drivers/stemodem/voicecall.c
index b9d91d2e..bf68f52a 100644
--- a/drivers/stemodem/voicecall.c
+++ b/drivers/stemodem/voicecall.c
@@ -109,7 +109,7 @@ static struct ofono_call *create_call(struct ofono_voicecall *vc, int type,
 
 	/* Generate a call structure for the waiting call */
 	call = g_try_new0(struct ofono_call, 1);
-	if (!call)
+	if (call == NULL)
 		return NULL;
 
 	call->type = type;
@@ -187,7 +187,7 @@ static void ste_dial(struct ofono_voicecall *vc,
 	struct cb_data *cbd = cb_data_new(cb, data);
 	char buf[256];
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	cbd->user = vc;
@@ -235,7 +235,7 @@ static void ste_template(const char *cmd, struct ofono_voicecall *vc,
 	struct voicecall_data *vd = ofono_voicecall_get_data(vc);
 	struct change_state_req *req = g_try_new0(struct change_state_req, 1);
 
-	if (!req)
+	if (req == NULL)
 		goto error;
 
 	req->vc = vc;
@@ -299,7 +299,7 @@ static void ste_release_specific(struct ofono_voicecall *vc, int id,
 	struct release_id_req *req = g_try_new0(struct release_id_req, 1);
 	char buf[32];
 
-	if (!req)
+	if (req == NULL)
 		goto error;
 
 	req->vc = vc;
@@ -379,13 +379,13 @@ static void ste_send_dtmf(struct ofono_voicecall *vc, const char *dtmf,
 	int s;
 	char *buf;
 
-	if (!cbd)
+	if (cbd == NULL)
 		goto error;
 
 	/* strlen("AT+VTS=) = 7 */
 	buf = g_try_new(char, len + 7);
 
-	if (!buf)
+	if (buf == NULL)
 		goto error;
 
 	sprintf(buf, "AT+VTS=%s", dtmf);
@@ -506,7 +506,7 @@ static void ecav_notify(GAtResult *result, gpointer user_data)
 
 		new_call = create_call(vc, call_type, direction, status,
 					num, num_type, clip_validity);
-		if (!new_call) {
+		if (new_call == NULL) {
 			ofono_error("Unable to malloc. "
 					"Call management is fubar");
 			return;
@@ -546,7 +546,7 @@ static int ste_voicecall_probe(struct ofono_voicecall *vc, unsigned int vendor,
 	struct voicecall_data *vd;
 
 	vd = g_try_new0(struct voicecall_data, 1);
-	if (!vd)
+	if (vd == NULL)
 		return -ENOMEM;
 
 	vd->chat = g_at_chat_clone(chat);