diff --git a/boards/arm/stm32f1/stm32_tiny/src/stm32_boot.c b/boards/arm/stm32f1/stm32_tiny/src/stm32_boot.c
index b392a99ddf8..3150b338e92 100644
--- a/boards/arm/stm32f1/stm32_tiny/src/stm32_boot.c
+++ b/boards/arm/stm32f1/stm32_tiny/src/stm32_boot.c
@@ -106,6 +106,8 @@ void board_late_initialize(void)
 {
   int ret = OK;
 
+  UNUSED(ret);
+
 #ifdef CONFIG_PWM
   /* Initialize PWM and register the PWM device. */
 
diff --git a/boards/arm/stm32f2/emw3162/src/stm32_wlan.c b/boards/arm/stm32f2/emw3162/src/stm32_wlan.c
index ff0e8ccaf1d..4396b94401a 100644
--- a/boards/arm/stm32f2/emw3162/src/stm32_wlan.c
+++ b/boards/arm/stm32f2/emw3162/src/stm32_wlan.c
@@ -142,7 +142,7 @@ bool bcmf_board_etheraddr(struct ether_addr *ethaddr)
  * Name: emw3162_wlan_initialize
  ****************************************************************************/
 
-int emw3162_wlan_initialize()
+int emw3162_wlan_initialize(void)
 {
   int ret;
 
diff --git a/boards/arm/stm32f2/photon/src/stm32_wlan.c b/boards/arm/stm32f2/photon/src/stm32_wlan.c
index 88bfa4561e9..f1548ca8a85 100644
--- a/boards/arm/stm32f2/photon/src/stm32_wlan.c
+++ b/boards/arm/stm32f2/photon/src/stm32_wlan.c
@@ -123,7 +123,7 @@ bool bcmf_board_etheraddr(struct ether_addr *ethaddr)
  * Name: photon_wlan_initialize
  ****************************************************************************/
 
-int photon_wlan_initialize()
+int photon_wlan_initialize(void)
 {
   int ret;