diff --git a/drivers/isimodem/gprs-context.c b/drivers/isimodem/gprs-context.c
index f458fcc3..bbf7ca92 100644
--- a/drivers/isimodem/gprs-context.c
+++ b/drivers/isimodem/gprs-context.c
@@ -347,50 +347,44 @@ static void send_context_authenticate(GIsiClient *client, void *opaque)
 	struct context_data *cd = opaque;
 	size_t username_len = strlen(cd->username);
 	size_t password_len = strlen(cd->password);
-	size_t sb_user_info_len = (3 + username_len + 3) & ~3;
-	size_t fill_sb_user_info_count =
-			sb_user_info_len - (3 + username_len);
-	uint8_t *fill_sb_user_info_data =
-			g_try_malloc0(fill_sb_user_info_count);
-	size_t sb_password_info_len = (3 + password_len + 3) & ~3;
-	size_t fill_sb_password_info_count =
-			sb_user_info_len - (3 + password_len);
-	uint8_t *fill_sb_password_info_data =
-			g_try_malloc0(fill_sb_password_info_count);
 
-	const unsigned char top[] = {
+	/* Pad the fields to the next 32bit boundary */
+	size_t sb_userinfo_len = (3 + username_len + 3) & ~3;
+	uint8_t userinfo_pad[sb_userinfo_len - (3 + username_len)];
+
+	size_t sb_password_info_len = (3 + password_len + 3) & ~3;
+	uint8_t password_pad[sb_password_info_len - (3 + password_len)];
+
+	const uint8_t top[] = {
 		GPDS_CONTEXT_AUTH_REQ,
 		cd->handle,
 		2,	/* sub blocks */
 		GPDS_USER_NAME_INFO,
-		sb_user_info_len,
+		sb_userinfo_len,
 		username_len,
 		/* Username goes here */
+		/* Possible padding goes here */
 	};
 
-	const unsigned char bottom[] = {
+	const uint8_t bottom[] = {
 		GPDS_PASSWORD_INFO,
 		sb_password_info_len,
 		password_len,
 		/* Password goes here */
+		/* Possible padding goes here */
 	};
 
 	const struct iovec iov[6] = {
 		{ (uint8_t *)top, sizeof(top) },
 		{ cd->username, username_len },
-		{ fill_sb_user_info_data, fill_sb_user_info_count },
+		{ userinfo_pad, sizeof(userinfo_pad) },
 		{ (uint8_t *)bottom, sizeof(bottom) },
 		{ cd->password, password_len },
-		{ fill_sb_password_info_data, fill_sb_password_info_count},
+		{ password_pad, sizeof(password_pad) },
 	};
 
-	if (fill_sb_user_info_data == NULL
-			&& fill_sb_user_info_count > 0)
-		gprs_up_fail(cd);
-
-	if (fill_sb_password_info_data == NULL
-			&& fill_sb_password_info_count > 0)
-		gprs_up_fail(cd);
+	memset(userinfo_pad, 0, sizeof(userinfo_pad));
+	memset(password_pad, 0, sizeof(password_pad));
 
 	if (!g_isi_client_vsend(client, iov, 6, context_auth_cb, cd, NULL))
 		gprs_up_fail(cd);
@@ -414,42 +408,38 @@ static void link_conf_cb(const GIsiMessage *msg, void *opaque)
 	struct context_data *cd = opaque;
 	size_t apn_len = strlen(cd->apn);
 	size_t sb_apn_info_len = (3 + apn_len + 3) & ~3;
-	size_t fill_count = sb_apn_info_len - (3 + apn_len);
-	uint8_t *fill_data = g_try_malloc0(fill_count);
+	size_t apn_pad[sb_apn_info_len - (3 + apn_len)];
 
-	if (fill_data == NULL && fill_count > 0)
-		return gprs_up_fail(cd);
+	const uint8_t req[] = {
+		GPDS_CONTEXT_CONFIGURE_REQ,
+		cd->handle,	/* context ID */
+		cd->type,	/* PDP type */
+		GPDS_CONT_TYPE_NORMAL,
+		cd->handle,	/* primary context ID */
+		0x00,		/* filler */
+		2,		/* sub blocks */
+		GPDS_DNS_ADDRESS_REQ_INFO,
+		4,		/* subblock length */
+		0, 0,		/* padding */
+		GPDS_APN_INFO,
+		sb_apn_info_len,
+		apn_len,
+		/* Possible padding goes here */
+	};
 
-	if (check_resp(msg, GPDS_LL_CONFIGURE_RESP, 2, cd, gprs_up_fail)) {
+	const struct iovec iov[3] = {
+		{ (uint8_t *)req, sizeof(req) },
+		{ cd->apn, apn_len },
+		{ apn_pad, sizeof(apn_pad) },
+	};
 
-		const unsigned char msg[] = {
-			GPDS_CONTEXT_CONFIGURE_REQ,
-			cd->handle,	/* context ID */
-			cd->type,	/* PDP type */
-			GPDS_CONT_TYPE_NORMAL,
-			cd->handle,	/* primary context ID */
-			0x00,		/* filler */
-			2,		/* sub blocks */
-			GPDS_DNS_ADDRESS_REQ_INFO,
-			4,		/* subblock length */
-			0, 0,		/* padding */
-			GPDS_APN_INFO,
-			sb_apn_info_len,
-			apn_len,
-		};
+	memset(apn_pad, 0, sizeof(apn_pad));
 
-		const struct iovec iov[3] = {
-			{ (uint8_t *)msg, sizeof(msg) },
-			{ cd->apn, apn_len },
-			{ fill_data, fill_count}
-		};
-
-		if (!g_isi_client_vsend_with_timeout(cd->client, iov, 3,
-				GPDS_TIMEOUT, context_conf_cb, cd, NULL))
-			return gprs_up_fail(cd);
-	} else
-		return gprs_up_fail(cd);
+	if (!check_resp(msg, GPDS_LL_CONFIGURE_RESP, 2, cd, gprs_up_fail))
+		return;
 
+	if (!g_isi_client_vsend(cd->client, iov, 3, context_conf_cb, cd, NULL))
+		gprs_up_fail(cd);
 }
 
 static void create_context_cb(const GIsiMessage *msg, void *opaque)