diff --git a/arch/arm/src/stm32l4/stm32l4_exti.h b/arch/arm/src/stm32l4/stm32l4_exti.h
index 4cfb52667b1..2f57229ea21 100644
--- a/arch/arm/src/stm32l4/stm32l4_exti.h
+++ b/arch/arm/src/stm32l4/stm32l4_exti.h
@@ -72,22 +72,22 @@ extern "C"
  * Description:
  *   Sets/clears GPIO based event and interrupt triggers.
  *
- * Parameters:
- *  - pinset: gpio pin configuration
- *  - rising/falling edge: enables
- *  - event:  generate event when set
- *  - func:   when non-NULL, generate interrupt
- *  - arg:    Argument passed to the interrupt callback
+ * Input Parameters:
+ *  pinset      - GPIO pin configuration
+ *  risingedge  - Enables interrupt on rising edges
+ *  fallingedge - Enables interrupt on falling edges
+ *  event       - Generate event when set
+ *  func        - When non-NULL, generate interrupt
+ *  arg         - Argument passed to the interrupt callback
  *
- * Returns:
- *  The previous value of the interrupt handler function pointer.  This value may,
- *  for example, be used to restore the previous handler when multiple handlers are
- *  used.
+ * Returned Value:
+ *  Zero (OK) is returned on success, otherwise a negated errno value is returned
+ *  to indicate the nature of the failure.
  *
  ************************************************************************************/
 
-xcpt_t stm32l4_gpiosetevent(uint32_t pinset, bool risingedge, bool fallingedge,
-                            bool event, xcpt_t func, void *arg);
+int stm32l4_gpiosetevent(uint32_t pinset, bool risingedge, bool fallingedge,
+                         bool event, xcpt_t func, void *arg);
 
 /****************************************************************************
  * Name: stm32l4_exti_alarm
diff --git a/arch/arm/src/stm32l4/stm32l4_exti_gpio.c b/arch/arm/src/stm32l4/stm32l4_exti_gpio.c
index e0eeabe529f..4a23c936320 100644
--- a/arch/arm/src/stm32l4/stm32l4_exti_gpio.c
+++ b/arch/arm/src/stm32l4/stm32l4_exti_gpio.c
@@ -61,8 +61,8 @@
 
 struct gpio_callback_s
 {
-  xcpt_t callback;
-  void  *arg;
+  xcpt_t callback;   /* Callback entry point */
+  void  *arg;        /* The argument that accompanies the callback */
 };
 
 /****************************************************************************
@@ -249,23 +249,25 @@ static int stm32l4_exti1510_isr(int irq, void *context, FAR void *arg)
  * Description:
  *   Sets/clears GPIO based event and interrupt triggers.
  *
- * Parameters:
- *  - pinset:      GPIO pin configuration
- *  - risingedge:  Enables interrupt on rising edges
- *  - fallingedge: Enables interrupt on falling edges
- *  - event:       Generate event when set
- *  - func:        When non-NULL, generate interrupt
- *  - arg:         Argument passed to the interrupt callback
+ * Description:
+ *   Sets/clears GPIO based event and interrupt triggers.
  *
- * Returns:
- *   The previous value of the interrupt handler function pointer.  This
- *   value may, for example, be used to restore the previous handler when
- *   multiple handlers are used.
+ * Input Parameters:
+ *  pinset      - GPIO pin configuration
+ *  risingedge  - Enables interrupt on rising edges
+ *  fallingedge - Enables interrupt on falling edges
+ *  event       - Generate event when set
+ *  func        - When non-NULL, generate interrupt
+ *  arg         - Argument passed to the interrupt callback
  *
- ****************************************************************************/
+ * Returned Value:
+ *  Zero (OK) is returned on success, otherwise a negated errno value is returned
+ *  to indicate the nature of the failure.
+ *
+ ************************************************************************************/
 
-xcpt_t stm32l4_gpiosetevent(uint32_t pinset, bool risingedge, bool fallingedge,
-                          bool event, xcpt_t func, void *arg)
+int stm32l4_gpiosetevent(uint32_t pinset, bool risingedge, bool fallingedge,
+                         bool event, xcpt_t func, void *arg)
 {
   struct gpio_callback_s *shared_cbs;
   uint32_t pin = pinset & GPIO_PIN_MASK;
@@ -323,7 +325,6 @@ xcpt_t stm32l4_gpiosetevent(uint32_t pinset, bool risingedge, bool fallingedge,
 
   /* Get the previous GPIO IRQ handler; Save the new IRQ handler. */
 
-  oldhandler                    = g_gpio_handlers[pin].callback;
   g_gpio_handlers[pin].callback = func;
   g_gpio_handlers[pin].arg      = arg;
 
@@ -385,5 +386,5 @@ xcpt_t stm32l4_gpiosetevent(uint32_t pinset, bool risingedge, bool fallingedge,
 
   /* Return the old IRQ handler */
 
-  return oldhandler;
+  return OK;
 }
diff --git a/arch/arm/src/stm32l4/stm32l4_gpio.h b/arch/arm/src/stm32l4/stm32l4_gpio.h
index 17ce32162fb..5d4f74d58dc 100644
--- a/arch/arm/src/stm32l4/stm32l4_gpio.h
+++ b/arch/arm/src/stm32l4/stm32l4_gpio.h
@@ -326,22 +326,22 @@ bool stm32l4_gpioread(uint32_t pinset);
  * Description:
  *   Sets/clears GPIO based event and interrupt triggers.
  *
- * Parameters:
- *  - pinset: gpio pin configuration
- *  - rising/falling edge: enables
- *  - event:  generate event when set
- *  - func:   when non-NULL, generate interrupt
- *  - arg:    Argument passed to the interrupt callback
+ * Input Parameters:
+ *  pinset      - GPIO pin configuration
+ *  risingedge  - Enables interrupt on rising edges
+ *  fallingedge - Enables interrupt on falling edges
+ *  event       - Generate event when set
+ *  func        - When non-NULL, generate interrupt
+ *  arg         - Argument passed to the interrupt callback
  *
- * Returns:
- *  The previous value of the interrupt handler function pointer.  This value may,
- *  for example, be used to restore the previous handler when multiple handlers are
- *  used.
+ * Returned Value:
+ *  Zero (OK) is returned on success, otherwise a negated errno value is returned
+ *  to indicate the nature of the failure.
  *
  ************************************************************************************/
 
-xcpt_t stm32l4_gpiosetevent(uint32_t pinset, bool risingedge, bool fallingedge,
-                            bool event, xcpt_t func, void *arg);
+int stm32l4_gpiosetevent(uint32_t pinset, bool risingedge, bool fallingedge,
+                         bool event, xcpt_t func, void *arg);
 
 /************************************************************************************
  * Function:  stm32l4_dumpgpio
diff --git a/configs/stm32l476-mdk/src/stm32_buttons.c b/configs/stm32l476-mdk/src/stm32_buttons.c
index 7dfc0469418..f87c9936ecc 100644
--- a/configs/stm32l476-mdk/src/stm32_buttons.c
+++ b/configs/stm32l476-mdk/src/stm32_buttons.c
@@ -152,15 +152,16 @@ uint8_t board_buttons(void)
 #ifdef CONFIG_ARCH_IRQBUTTONS
 xcpt_t board_button_irq(int id, xcpt_t irqhandler, FAR void *arg)
 {
-  xcpt_t oldhandler = NULL;
+  int ret = OK;
 
   if (id >= MIN_IRQBUTTON && id <= MAX_IRQBUTTON)
     {
-      oldhandler = stm32l4_gpiosetevent(g_buttons[id], true, true, true,
-                                        irqhandler, arg);
+      ret = stm32l4_gpiosetevent(g_buttons[id], true, true, true,
+                                 irqhandler, arg);
     }
 
-  return oldhandler;
+  UNUSED(ret);
+  return NULL;
 }
 #endif
 #endif /* CONFIG_ARCH_BUTTONS */
diff --git a/configs/stm32l476vg-disco/src/stm32_buttons.c b/configs/stm32l476vg-disco/src/stm32_buttons.c
index 7fc0c09d8a9..8e8f43313f2 100644
--- a/configs/stm32l476vg-disco/src/stm32_buttons.c
+++ b/configs/stm32l476vg-disco/src/stm32_buttons.c
@@ -327,17 +327,17 @@ uint8_t board_buttons(void)
 #ifdef CONFIG_ARCH_IRQBUTTONS
 xcpt_t board_button_irq(int id, xcpt_t irqhandler, FAR void *arg)
 {
-  xcpt_t oldhandler = NULL;
+  int ret = OK;
 
   /* The following should be atomic */
 
   if (id >= MIN_IRQBUTTON && id <= MAX_IRQBUTTON)
     {
-      oldhandler = stm32l4_gpiosetevent(g_buttons[id], true, true, true,
-                                        irqhandler, arg);
+      ret = stm32l4_gpiosetevent(g_buttons[id], true, true, true, irqhandler, arg);
     }
 
-  return oldhandler;
+  UNUSED(ret);
+  return NULL;
 }
 #endif
 #endif /* CONFIG_ARCH_BUTTONS */
diff --git a/configs/stm32l476vg-disco/src/stm32_usb.c b/configs/stm32l476vg-disco/src/stm32_usb.c
index 0b08a9264d2..0f51871e1ac 100644
--- a/configs/stm32l476vg-disco/src/stm32_usb.c
+++ b/configs/stm32l476vg-disco/src/stm32_usb.c
@@ -311,7 +311,8 @@ void stm32l4_usbhost_vbusdrive(int iface, bool enable)
 #ifdef CONFIG_USBHOST
 xcpt_t stm32l4_setup_overcurrent(xcpt_t handler)
 {
-  return stm32l4_gpiosetevent(GPIO_OTGFS_OVER, true, true, true, handler, NULL);
+  (void)stm32l4_gpiosetevent(GPIO_OTGFS_OVER, true, true, true, handler, NULL);
+  return NULL;
 }
 #endif