diff --git a/arch/arm/src/stm32/stm32_exti_pwr.c b/arch/arm/src/stm32/stm32_exti_pwr.c
index 0fcb2f78038..5ab6138ac4b 100644
--- a/arch/arm/src/stm32/stm32_exti_pwr.c
+++ b/arch/arm/src/stm32/stm32_exti_pwr.c
@@ -158,7 +158,5 @@ int stm32_exti_pvd(bool risingedge, bool fallingedge, bool event,
               func ? 0 : EXTI_PVD_LINE,
               func ? EXTI_PVD_LINE : 0);
 
-  /* Return the old IRQ handler */
-
   return OK;
 }
diff --git a/arch/arm/src/stm32f7/stm32_exti_pwr.c b/arch/arm/src/stm32f7/stm32_exti_pwr.c
index e3418e00694..09d064e930e 100644
--- a/arch/arm/src/stm32f7/stm32_exti_pwr.c
+++ b/arch/arm/src/stm32f7/stm32_exti_pwr.c
@@ -166,7 +166,5 @@ int stm32_exti_pvd(bool risingedge, bool fallingedge, bool event,
               func ? 0 : EXTI_PVD_LINE,
               func ? EXTI_PVD_LINE : 0);
 
-  /* Return the old IRQ handler */
-
   return OK;
 }
diff --git a/arch/arm/src/stm32l4/stm32l4_exti.h b/arch/arm/src/stm32l4/stm32l4_exti.h
index d090ea7d483..e69ba9a51af 100644
--- a/arch/arm/src/stm32l4/stm32l4_exti.h
+++ b/arch/arm/src/stm32l4/stm32l4_exti.h
@@ -127,15 +127,14 @@ xcpt_t stm32l4_exti_alarm(bool risingedge, bool fallingedge, bool event,
  *  - 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.
+ *   Zero (OK) returned on success; a negated errno value is returned on
+ *   failure.
  *
  ****************************************************************************/
 
 #ifdef CONFIG_STM32L4_COMP
-xcpt_t stm32l4_exti_comp(int cmp, bool risingedge, bool fallingedge,
-                         bool event, xcpt_t func, void *arg);
+int stm32l4_exti_comp(int cmp, bool risingedge, bool fallingedge,
+                      bool event, xcpt_t func, void *arg);
 #endif
 
 #undef EXTERN
diff --git a/arch/arm/src/stm32l4/stm32l4_exti_comp.c b/arch/arm/src/stm32l4/stm32l4_exti_comp.c
index 7c508a11668..a1295b6970b 100644
--- a/arch/arm/src/stm32l4/stm32l4_exti_comp.c
+++ b/arch/arm/src/stm32l4/stm32l4_exti_comp.c
@@ -129,16 +129,14 @@ static int stm32l4_exti_comp_isr(int irq, void *context)
  *  - 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.
+ *   Zero (OK) returned on success; a negated errno value is returned on
+ *   failure.
  *
  ****************************************************************************/
 
-xcpt_t stm32l4_exti_comp(int cmp, bool risingedge, bool fallingedge,
-                         bool event, xcpt_t func, void *arg)
+int stm32l4_exti_comp(int cmp, bool risingedge, bool fallingedge,
+                      bool event, xcpt_t func, void *arg)
 {
-  xcpt_t oldhandler;
   irqstate_t flags;
   uint32_t ln = g_comp_lines[cmp];
 
@@ -152,7 +150,7 @@ xcpt_t stm32l4_exti_comp(int cmp, bool risingedge, bool fallingedge,
 
   if (func != NULL)
     {
-      irq_attach(STM32L4_IRQ_COMP, stm32l4_exti_comp_isr);
+      irq_attach(STM32L4_IRQ_COMP, stm32l4_exti_comp_isr, NULL);
       up_enable_irq(STM32L4_IRQ_COMP);
     }
   else
@@ -172,15 +170,11 @@ xcpt_t stm32l4_exti_comp(int cmp, bool risingedge, bool fallingedge,
 
     /* Get the previous IRQ handler and save the new IRQ handler. */
 
-    oldhandler                    = g_comp_handlers[cmp].callback;
     g_comp_handlers[cmp].callback = func;
     g_comp_handlers[cmp].arg      = arg;
 
     /* Leave the critical section */
 
     leave_critical_section(flags);
-
-    /* Return the old IRQ handler */
-
-    return oldhandler;
+    return OK;
 }
diff --git a/arch/arm/src/stm32l4/stm32l4_exti_pwr.c b/arch/arm/src/stm32l4/stm32l4_exti_pwr.c
index 144e08a3f7e..ab19f6f3cb9 100644
--- a/arch/arm/src/stm32l4/stm32l4_exti_pwr.c
+++ b/arch/arm/src/stm32l4/stm32l4_exti_pwr.c
@@ -157,7 +157,5 @@ int stm32l4_exti_pvd(bool risingedge, bool fallingedge, bool event,
               func ? 0 : EXTI1_PVD_LINE,
               func ? EXTI1_PVD_LINE : 0);
 
-  /* Return the old IRQ handler */
-
   return OK;
 }