diff --git a/subsys/bluetooth/common/log.c b/subsys/bluetooth/common/log.c
index 2ca11b2b68f..b6e6526191f 100644
--- a/subsys/bluetooth/common/log.c
+++ b/subsys/bluetooth/common/log.c
@@ -25,7 +25,7 @@ const char *bt_hex_real(const void *buf, size_t len)
 	static const char hex[] = "0123456789abcdef";
 	static char str[129];
 	const u8_t *b = buf;
-	int i;
+	size_t i;
 
 	len = MIN(len, (sizeof(str) - 1) / 2);
 
diff --git a/subsys/bluetooth/host/crypto.c b/subsys/bluetooth/host/crypto.c
index d1ad31474d0..94e3e95dd1a 100644
--- a/subsys/bluetooth/host/crypto.c
+++ b/subsys/bluetooth/host/crypto.c
@@ -33,7 +33,8 @@ static int prng_reseed(struct tc_hmac_prng_struct *h)
 {
 	u8_t seed[32];
 	s64_t extra;
-	int ret, i;
+	size_t i;
+	int ret;
 
 	for (i = 0; i < (sizeof(seed) / 8); i++) {
 		struct bt_hci_rp_le_rand *rp;
diff --git a/subsys/bluetooth/host/gatt.c b/subsys/bluetooth/host/gatt.c
index 5c3cac0d4c2..4d2b1ff2156 100644
--- a/subsys/bluetooth/host/gatt.c
+++ b/subsys/bluetooth/host/gatt.c
@@ -1162,7 +1162,7 @@ static u16_t find_static_attr(const struct bt_gatt_attr *attr)
 	u16_t handle = 1;
 
 	Z_STRUCT_SECTION_FOREACH(bt_gatt_service_static, static_svc) {
-		for (int i = 0; i < static_svc->attr_count; i++, handle++) {
+		for (size_t i = 0; i < static_svc->attr_count; i++, handle++) {
 			if (attr == &static_svc->attrs[i]) {
 				return handle;
 			}
@@ -1305,7 +1305,7 @@ static void foreach_attr_type_dyndb(u16_t start_handle, u16_t end_handle,
 				    bt_gatt_attr_func_t func, void *user_data)
 {
 #if defined(CONFIG_BT_GATT_DYNAMIC_DB)
-	int i;
+	size_t i;
 	struct bt_gatt_service *svc;
 
 	SYS_SLIST_FOR_EACH_CONTAINER(&db, svc, node) {
@@ -1341,7 +1341,7 @@ void bt_gatt_foreach_attr_type(u16_t start_handle, u16_t end_handle,
 			       const void *attr_data, uint16_t num_matches,
 			       bt_gatt_attr_func_t func, void *user_data)
 {
-	int i;
+	size_t i;
 
 	if (!num_matches) {
 		num_matches = UINT16_MAX;
@@ -3860,7 +3860,7 @@ static int ccc_set(const char *name, size_t len_rd, settings_read_cb read_cb,
 			load.entry = ccc_store;
 			load.count = len / sizeof(*ccc_store);
 
-			for (int i = 0; i < load.count; i++) {
+			for (size_t i = 0; i < load.count; i++) {
 				BT_DBG("Read CCC: handle 0x%04x value 0x%04x",
 				       ccc_store[i].handle, ccc_store[i].value);
 			}
@@ -4183,7 +4183,7 @@ int bt_gatt_store_ccc(u8_t id, const bt_addr_le_t *addr)
 	BT_DBG("Stored CCCs for %s (%s)", bt_addr_le_str(addr),
 	       log_strdup(key));
 	if (len) {
-		for (int i = 0; i < save.count; i++) {
+		for (size_t i = 0; i < save.count; i++) {
 			BT_DBG("  CCC: handle 0x%04x value 0x%04x",
 			       save.store[i].handle, save.store[i].value);
 		}
diff --git a/subsys/bluetooth/host/hci_core.c b/subsys/bluetooth/host/hci_core.c
index dba0c6a8c57..c18cd82ef4e 100644
--- a/subsys/bluetooth/host/hci_core.c
+++ b/subsys/bluetooth/host/hci_core.c
@@ -2192,7 +2192,7 @@ bool bt_le_conn_params_valid(const struct bt_le_conn_param *param)
 
 	if (param->timeout < 10 || param->timeout > 3200 ||
 	    ((param->timeout * 4U) <=
-	     ((1 + param->latency) * param->interval_max))) {
+	     ((1U + param->latency) * param->interval_max))) {
 		return false;
 	}
 
@@ -6965,7 +6965,7 @@ static bool valid_adv_param(const struct bt_le_adv_param *param, bool dir_adv)
 
 static inline bool ad_has_name(const struct bt_data *ad, size_t ad_len)
 {
-	int i;
+	size_t i;
 
 	for (i = 0; i < ad_len; i++) {
 		if (ad[i].type == BT_DATA_NAME_COMPLETE ||
diff --git a/subsys/bluetooth/shell/bt.c b/subsys/bluetooth/shell/bt.c
index 0e94bd0480e..6c86d42770e 100644
--- a/subsys/bluetooth/shell/bt.c
+++ b/subsys/bluetooth/shell/bt.c
@@ -434,7 +434,7 @@ static int cmd_hci_cmd(const struct shell *shell, size_t argc, char *argv[])
 	ocf = strtoul(argv[2], NULL, 16);
 
 	if (argc > 3) {
-		int i;
+		size_t i;
 
 		buf = bt_hci_cmd_create(BT_OP(ogf, ocf), argc - 3);
 
diff --git a/subsys/bluetooth/shell/gatt.c b/subsys/bluetooth/shell/gatt.c
index 6bbead3505c..872e64e2c66 100644
--- a/subsys/bluetooth/shell/gatt.c
+++ b/subsys/bluetooth/shell/gatt.c
@@ -266,7 +266,8 @@ static int cmd_read(const struct shell *shell, size_t argc, char *argv[])
 static int cmd_mread(const struct shell *shell, size_t argc, char *argv[])
 {
 	u16_t h[8];
-	int i, err;
+	size_t i;
+	int err;
 
 	if (!default_conn) {
 		shell_error(shell, "Not connected");
@@ -382,8 +383,7 @@ static int cmd_write(const struct shell *shell, size_t argc, char *argv[])
 	write_params.func = write_func;
 
 	if (argc == 5) {
-		size_t len;
-		int i;
+		size_t len, i;
 
 		len = MIN(strtoul(argv[4], NULL, 16), sizeof(gatt_write_buf));
 
@@ -977,7 +977,7 @@ static u8_t set_cb(const struct bt_gatt_attr *attr, void *user_data)
 {
 	struct set_data *data = user_data;
 	u8_t buf[256];
-	int i;
+	size_t i;
 	ssize_t ret;
 
 	if (!attr->write) {