diff --git a/src/drivers/boards/common/stm32/board_identity.c b/src/drivers/boards/common/stm32/board_identity.c
index fa1706b4d2..41e52a186c 100644
--- a/src/drivers/boards/common/stm32/board_identity.c
+++ b/src/drivers/boards/common/stm32/board_identity.c
@@ -73,7 +73,7 @@ __EXPORT void board_get_uuid32(uuid_uint32_t uuid_words)
 {
 	uint32_t *chip_uuid = (uint32_t *) STM32_SYSMEM_UID;
 
-	for (int i = 0; i < PX4_CPU_UUID_WORD32_LENGTH; i++) {
+	for (unsigned i = 0; i < PX4_CPU_UUID_WORD32_LENGTH; i++) {
 		uuid_words[i] = chip_uuid[i];
 	}
 }
@@ -87,7 +87,7 @@ int board_get_uuid32_formated(char *format_buffer, int size,
 	int offset = 0;
 	int sep_size = seperator ? strlen(seperator) : 0;
 
-	for (int i = 0; i < PX4_CPU_UUID_WORD32_LENGTH; i++) {
+	for (unsigned i = 0; i < PX4_CPU_UUID_WORD32_LENGTH; i++) {
 		offset += snprintf(&format_buffer[offset], size - offset, format, uuid[i]);
 
 		if (sep_size && i < PX4_CPU_UUID_WORD32_LENGTH - 1) {
@@ -104,7 +104,7 @@ int board_get_mfguid(mfguid_t mfgid)
 	uint32_t *chip_uuid = (uint32_t *) STM32_SYSMEM_UID;
 	uint32_t  *rv = (uint32_t *) &mfgid[0];
 
-	for (int i = 0; i < PX4_CPU_UUID_WORD32_LENGTH; i++) {
+	for (unsigned i = 0; i < PX4_CPU_UUID_WORD32_LENGTH; i++) {
 		*rv++ = SWAP_UINT32(chip_uuid[(PX4_CPU_UUID_WORD32_LENGTH - 1) - i]);
 	}
 
@@ -118,7 +118,7 @@ int board_get_mfguid_formated(char *format_buffer, int size)
 	board_get_mfguid(mfguid);
 	int offset  = 0;
 
-	for (unsigned int i = 0; i < PX4_CPU_MFGUID_BYTE_LENGTH; i++) {
+	for (unsigned i = 0; i < PX4_CPU_MFGUID_BYTE_LENGTH; i++) {
 		offset += snprintf(&format_buffer[offset], size - offset, "%02x", mfguid[i]);
 	}