diff --git a/src/simutil.c b/src/simutil.c
index 9287df17..e7fbfaf0 100644
--- a/src/simutil.c
+++ b/src/simutil.c
@@ -793,7 +793,7 @@ static char *sim_network_name_parse(const unsigned char *buffer, int length,
 		spare_bits = dcs & 0x07;
 		num_char = (length * 8 - spare_bits) / 7;
 
-		unpacked_buf = unpack_7bit(buffer, length, 0, FALSE,
+		unpacked_buf = unpack_7bit(buffer, length, 0, false,
 						num_char, &written, 0);
 		if (unpacked_buf == NULL)
 			break;
diff --git a/src/smsutil.c b/src/smsutil.c
index 90f158b2..971717cf 100644
--- a/src/smsutil.c
+++ b/src/smsutil.c
@@ -560,7 +560,7 @@ gboolean sms_encode_address_field(const struct sms_address *in, gboolean sc,
 			return FALSE;
 		}
 
-		r = pack_7bit_own_buf(gsm, written, 0, FALSE, &packed, 0, p);
+		r = pack_7bit_own_buf(gsm, written, 0, false, &packed, 0, p);
 
 		g_free(gsm);
 
@@ -667,7 +667,7 @@ gboolean sms_decode_address_field(const unsigned char *pdu, int len,
 			return TRUE;
 		}
 
-		res = unpack_7bit(pdu + *offset, byte_len, 0, FALSE, chars,
+		res = unpack_7bit(pdu + *offset, byte_len, 0, false, chars,
 					&written, 0);
 
 		*offset = *offset + (addr_len + 1) / 2;
@@ -1330,7 +1330,7 @@ gboolean sms_decode_unpacked_stk_pdu(const unsigned char *pdu, int len,
 	if ((len - offset) < out->submit.udl)
 		return FALSE;
 
-	pack_7bit_own_buf(pdu + offset, out->submit.udl, 0, FALSE,
+	pack_7bit_own_buf(pdu + offset, out->submit.udl, 0, false,
 				NULL, 0, out->submit.ud);
 
 	return TRUE;
@@ -2265,7 +2265,7 @@ char *sms_decode_text(GSList *sms_list)
 
 			if (unpack_7bit_own_buf(ud + taken,
 						udl_in_bytes - taken,
-						taken, FALSE, max_chars,
+						taken, false, max_chars,
 						&written, 0, buf) == NULL)
 				continue;
 
@@ -3629,7 +3629,7 @@ GSList *sms_text_prepare_with_alphabet(const char *to, const char *utf8,
 
 	if (gsm_encoded && (written <= sms_text_capacity_gsm(160, offset))) {
 		template.submit.udl = written + (offset * 8 + 6) / 7;
-		pack_7bit_own_buf(gsm_encoded, written, offset, FALSE, NULL,
+		pack_7bit_own_buf(gsm_encoded, written, offset, false, NULL,
 					0, template.submit.ud + offset);
 
 		g_free(gsm_encoded);
@@ -3686,7 +3686,7 @@ GSList *sms_text_prepare_with_alphabet(const char *to, const char *utf8,
 
 			template.submit.udl = chunk + (offset * 8 + 6) / 7;
 			pack_7bit_own_buf(gsm_encoded + written, chunk,
-						offset, FALSE, NULL, 0,
+						offset, false, NULL, 0,
 						template.submit.ud + offset);
 		} else {
 			chunk = 140 - offset;
@@ -4090,7 +4090,7 @@ char *cbs_decode_text(GSList *cbs_list, char *iso639_lang)
 				taken = sms_udh_iter_get_udh_length(&iter) + 1;
 
 			unpack_7bit_own_buf(cbs->ud + taken, 82 - taken,
-						taken, FALSE, 2,
+						taken, false, 2,
 						NULL, 0,
 						(unsigned char *)iso639_lang);
 			iso639_lang[2] = '\0';
@@ -4123,7 +4123,7 @@ char *cbs_decode_text(GSList *cbs_list, char *iso639_lang)
 				sms_text_capacity_gsm(CBS_MAX_GSM_CHARS, taken);
 
 			unpack_7bit_own_buf(ud + taken, 82 - taken,
-						taken, FALSE, max_chars,
+						taken, false, max_chars,
 						&written, 0, unpacked);
 
 			i = iso639 ? 3 : 0;
@@ -4730,7 +4730,7 @@ char *ussd_decode(int dcs, int len, const unsigned char *data)
 	case SMS_CHARSET_7BIT:
 	{
 		long written;
-		unsigned char *unpacked = unpack_7bit(data, len, 0, TRUE, 0,
+		unsigned char *unpacked = unpack_7bit(data, len, 0, true, 0,
 							&written, 0);
 		if (unpacked == NULL)
 			return NULL;
@@ -4770,7 +4770,7 @@ gboolean ussd_encode(const char *str, long *items_written, unsigned char *pdu)
 		return FALSE;
 	}
 
-	pack_7bit_own_buf(converted, written, 0, TRUE, &num_packed, 0, pdu);
+	pack_7bit_own_buf(converted, written, 0, true, &num_packed, 0, pdu);
 	g_free(converted);
 
 	if (num_packed < 1)
diff --git a/src/stkutil.c b/src/stkutil.c
index 9992f6c5..2ba8dbc8 100644
--- a/src/stkutil.c
+++ b/src/stkutil.c
@@ -94,7 +94,7 @@ static char *decode_text(unsigned char dcs, int len, const unsigned char *data)
 	{
 		long written;
 		unsigned long max_to_unpack = len * 8 / 7;
-		unsigned char *unpacked = unpack_7bit(data, len, 0, FALSE,
+		unsigned char *unpacked = unpack_7bit(data, len, 0, false,
 							max_to_unpack,
 							&written, 0);
 		if (unpacked == NULL)
@@ -4040,7 +4040,7 @@ static gboolean stk_tlv_builder_append_gsm_packed(struct stk_tlv_builder *iter,
 		return FALSE;
 	}
 
-	pack_7bit_own_buf(gsm, len, 0, FALSE, &written, 0,
+	pack_7bit_own_buf(gsm, len, 0, false, &written, 0,
 				iter->value + iter->len + 1);
 	g_free(gsm);
 
diff --git a/src/ussd.c b/src/ussd.c
index df1136f5..5b7f0152 100644
--- a/src/ussd.c
+++ b/src/ussd.c
@@ -34,7 +34,6 @@
 
 #include "common.h"
 #include "smsutil.h"
-#include "util.h"
 
 #define MAX_USSD_LENGTH 160
 
diff --git a/src/util.c b/src/util.c
index ffdd1ae8..34d64b94 100644
--- a/src/util.c
+++ b/src/util.c
@@ -2688,7 +2688,7 @@ static unsigned short unicode_single_shift_lookup(struct conversion_table *t,
 	return codepoint_lookup(&key, t->single_u, t->single_len_u);
 }
 
-static gboolean populate_locking_shift(struct conversion_table *t,
+static bool populate_locking_shift(struct conversion_table *t,
 					enum gsm_dialect lang)
 {
 	switch (lang) {
@@ -2697,85 +2697,85 @@ static gboolean populate_locking_shift(struct conversion_table *t,
 		t->locking_g = def_gsm;
 		t->locking_u = def_unicode;
 		t->locking_len_u = L_ARRAY_SIZE(def_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_TURKISH:
 		t->locking_g = tur_gsm;
 		t->locking_u = tur_unicode;
 		t->locking_len_u = L_ARRAY_SIZE(tur_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_PORTUGUESE:
 		t->locking_g = por_gsm;
 		t->locking_u = por_unicode;
 		t->locking_len_u = L_ARRAY_SIZE(por_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_BENGALI:
 		t->locking_g = ben_gsm;
 		t->locking_u = ben_unicode;
 		t->locking_len_u = L_ARRAY_SIZE(ben_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_GUJARATI:
                 t->locking_g = guj_gsm;
                 t->locking_u = guj_unicode;
                 t->locking_len_u = L_ARRAY_SIZE(guj_unicode);
-                return TRUE;
+                return true;
 
 	case GSM_DIALECT_HINDI:
 		t->locking_g = hin_gsm;
 		t->locking_u = hin_unicode;
 		t->locking_len_u = L_ARRAY_SIZE(hin_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_KANNADA:
 		t->locking_g = kan_gsm;
 		t->locking_u = kan_unicode;
 		t->locking_len_u = L_ARRAY_SIZE(kan_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_MALAYALAM:
 		t->locking_g = mal_gsm;
 		t->locking_u = mal_unicode;
 		t->locking_len_u = L_ARRAY_SIZE(mal_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_ORIYA:
 		t->locking_g = ori_gsm;
 		t->locking_u = ori_unicode;
 		t->locking_len_u = L_ARRAY_SIZE(ori_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_PUNJABI:
 		t->locking_g = pun_gsm;
 		t->locking_u = pun_unicode;
 		t->locking_len_u = L_ARRAY_SIZE(pun_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_TAMIL:
 		t->locking_g = tam_gsm;
 		t->locking_u = tam_unicode;
 		t->locking_len_u = L_ARRAY_SIZE(tam_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_TELUGU:
 		t->locking_g = tel_gsm;
 		t->locking_u = tel_unicode;
 		t->locking_len_u = L_ARRAY_SIZE(tel_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_URDU:
 		t->locking_g = urd_gsm;
 		t->locking_u = urd_unicode;
 		t->locking_len_u = L_ARRAY_SIZE(urd_unicode);
-		return TRUE;
+		return true;
         }
 
-	return FALSE;
+	return false;
 }
 
-static gboolean populate_single_shift(struct conversion_table *t,
+static bool populate_single_shift(struct conversion_table *t,
 					enum gsm_dialect lang)
 {
 	switch (lang) {
@@ -2784,104 +2784,104 @@ static gboolean populate_single_shift(struct conversion_table *t,
 		t->single_len_g = L_ARRAY_SIZE(def_ext_gsm);
 		t->single_u = def_ext_unicode;
 		t->single_len_u = L_ARRAY_SIZE(def_ext_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_TURKISH:
 		t->single_g = tur_ext_gsm;
 		t->single_len_g = L_ARRAY_SIZE(tur_ext_gsm);
 		t->single_u = tur_ext_unicode;
 		t->single_len_u = L_ARRAY_SIZE(tur_ext_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_SPANISH:
 		t->single_g = spa_ext_gsm;
 		t->single_len_g = L_ARRAY_SIZE(spa_ext_gsm);
 		t->single_u = spa_ext_unicode;
 		t->single_len_u = L_ARRAY_SIZE(spa_ext_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_PORTUGUESE:
 		t->single_g = por_ext_gsm;
 		t->single_len_g = L_ARRAY_SIZE(por_ext_gsm);
 		t->single_u = por_ext_unicode;
 		t->single_len_u = L_ARRAY_SIZE(por_ext_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_BENGALI:
 		t->single_g = ben_ext_gsm;
 		t->single_len_g = L_ARRAY_SIZE(ben_ext_gsm);
 		t->single_u = ben_ext_unicode;
 		t->single_len_u = L_ARRAY_SIZE(ben_ext_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_GUJARATI:
                 t->single_g = guj_ext_gsm;
                 t->single_len_g = L_ARRAY_SIZE(guj_ext_gsm);
                 t->single_u = guj_ext_unicode;
                 t->single_len_u = L_ARRAY_SIZE(guj_ext_unicode);
-                return TRUE;
+                return true;
 
 	case GSM_DIALECT_HINDI:
 		t->single_g = hin_ext_gsm;
 		t->single_len_g = L_ARRAY_SIZE(hin_ext_gsm);
 		t->single_u = hin_ext_unicode;
 		t->single_len_u = L_ARRAY_SIZE(hin_ext_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_KANNADA:
 		t->single_g = kan_ext_gsm;
 		t->single_len_g = L_ARRAY_SIZE(kan_ext_gsm);
 		t->single_u = kan_ext_unicode;
 		t->single_len_u = L_ARRAY_SIZE(kan_ext_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_MALAYALAM:
 		t->single_g = mal_ext_gsm;
 		t->single_len_g = L_ARRAY_SIZE(mal_ext_gsm);
 		t->single_u = mal_ext_unicode;
 		t->single_len_u = L_ARRAY_SIZE(mal_ext_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_ORIYA:
 		t->single_g = ori_ext_gsm;
 		t->single_len_g = L_ARRAY_SIZE(ori_ext_gsm);
 		t->single_u = ori_ext_unicode;
 		t->single_len_u = L_ARRAY_SIZE(ori_ext_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_PUNJABI:
 		t->single_g = pun_ext_gsm;
 		t->single_len_g = L_ARRAY_SIZE(pun_ext_gsm);
 		t->single_u = pun_ext_unicode;
 		t->single_len_u = L_ARRAY_SIZE(pun_ext_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_TAMIL:
 		t->single_g = tam_ext_gsm;
 		t->single_len_g = L_ARRAY_SIZE(tam_ext_gsm);
 		t->single_u = tam_ext_unicode;
 		t->single_len_u = L_ARRAY_SIZE(tam_ext_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_TELUGU:
 		t->single_g = tel_ext_gsm;
 		t->single_len_g = L_ARRAY_SIZE(tel_ext_gsm);
 		t->single_u = tel_ext_unicode;
 		t->single_len_u = L_ARRAY_SIZE(tel_ext_unicode);
-		return TRUE;
+		return true;
 
 	case GSM_DIALECT_URDU:
 		t->single_g = urd_ext_gsm;
 		t->single_len_g = L_ARRAY_SIZE(urd_ext_gsm);
 		t->single_u = urd_ext_unicode;
 		t->single_len_u = L_ARRAY_SIZE(urd_ext_unicode);
-		return TRUE;
+		return true;
         }
 
-	return FALSE;
+	return false;
 }
 
-static gboolean conversion_table_init(struct conversion_table *t,
+static bool conversion_table_init(struct conversion_table *t,
 					enum gsm_dialect locking,
 					enum gsm_dialect single)
 {
@@ -2917,7 +2917,7 @@ char *convert_gsm_to_utf8_with_lang(const unsigned char *text, long len,
 
 	struct conversion_table t;
 
-	if (conversion_table_init(&t, locking_lang, single_lang) == FALSE)
+	if (!conversion_table_init(&t, locking_lang, single_lang))
 		return NULL;
 
 	if (len < 0 && !terminator)
@@ -3035,7 +3035,7 @@ unsigned char *convert_utf8_to_gsm_with_lang(const char *text, long len,
 	long res_len;
 	long i;
 
-	if (conversion_table_init(&t, locking_lang, single_lang) == FALSE)
+	if (!conversion_table_init(&t, locking_lang, single_lang))
 		return NULL;
 
 	in = text;
@@ -3331,7 +3331,7 @@ char *encode_hex(const unsigned char *in, long len, unsigned char terminator)
 }
 
 unsigned char *unpack_7bit_own_buf(const unsigned char *in, long len,
-					int byte_offset, gboolean ussd,
+					int byte_offset, bool ussd,
 					long max_to_unpack, long *items_written,
 					unsigned char terminator,
 					unsigned char *buf)
@@ -3409,7 +3409,7 @@ unsigned char *unpack_7bit_own_buf(const unsigned char *in, long len,
 }
 
 unsigned char *unpack_7bit(const unsigned char *in, long len, int byte_offset,
-				gboolean ussd, long max_to_unpack,
+				bool ussd, long max_to_unpack,
 				long *items_written, unsigned char terminator)
 {
 	unsigned char *buf = g_new(unsigned char,
@@ -3420,7 +3420,7 @@ unsigned char *unpack_7bit(const unsigned char *in, long len, int byte_offset,
 }
 
 unsigned char *pack_7bit_own_buf(const unsigned char *in, long len,
-					int byte_offset, gboolean ussd,
+					int byte_offset, bool ussd,
 					long *items_written,
 					unsigned char terminator,
 					unsigned char *buf)
@@ -3493,7 +3493,7 @@ unsigned char *pack_7bit_own_buf(const unsigned char *in, long len,
 }
 
 unsigned char *pack_7bit(const unsigned char *in, long len, int byte_offset,
-				gboolean ussd, long *items_written,
+				bool ussd, long *items_written,
 				unsigned char terminator)
 {
 	int bits = 7 - (byte_offset % 7);
@@ -3540,8 +3540,8 @@ char *sim_string_to_utf8(const unsigned char *buffer, int length)
 	char *utf8 = NULL;
 	char *out;
 
-	if (conversion_table_init(&t, GSM_DIALECT_DEFAULT,
-					GSM_DIALECT_DEFAULT) == FALSE)
+	if (!conversion_table_init(&t, GSM_DIALECT_DEFAULT,
+					GSM_DIALECT_DEFAULT))
 		return NULL;
 
 	if (length < 1)
@@ -3744,7 +3744,7 @@ unsigned char *convert_ucs2_to_gsm_with_lang(const unsigned char *text,
 	long res_len;
 	long i;
 
-	if (conversion_table_init(&t, locking_lang, single_lang) == FALSE)
+	if (!conversion_table_init(&t, locking_lang, single_lang))
 		return NULL;
 
 	if (len < 1 || len % 2)
diff --git a/src/util.h b/src/util.h
index aaaed8ce..df3763b1 100644
--- a/src/util.h
+++ b/src/util.h
@@ -19,6 +19,8 @@
  *
  */
 
+#include <stdbool.h>
+
 enum gsm_dialect {
 	GSM_DIALECT_DEFAULT = 0,
 	GSM_DIALECT_TURKISH,
@@ -75,23 +77,23 @@ char *encode_hex(const unsigned char *in, long len,
 			unsigned char terminator);
 
 unsigned char *unpack_7bit_own_buf(const unsigned char *in, long len,
-					int byte_offset, gboolean ussd,
+					int byte_offset, bool ussd,
 					long max_to_unpack, long *items_written,
 					unsigned char terminator,
 					unsigned char *buf);
 
 unsigned char *unpack_7bit(const unsigned char *in, long len, int byte_offset,
-				gboolean ussd, long max_to_unpack,
+				bool ussd, long max_to_unpack,
 				long *items_written, unsigned char terminator);
 
 unsigned char *pack_7bit_own_buf(const unsigned char *in, long len,
-					int byte_offset, gboolean ussd,
+					int byte_offset, bool ussd,
 					long *items_written,
 					unsigned char terminator,
 					unsigned char *buf);
 
 unsigned char *pack_7bit(const unsigned char *in, long len, int byte_offset,
-				gboolean ussd,
+				bool ussd,
 				long *items_written, unsigned char terminator);
 
 char *sim_string_to_utf8(const unsigned char *buffer, int length);