diff --git a/arch/arm/src/kinetis/kinetis_pinirq.c b/arch/arm/src/kinetis/kinetis_pinirq.c
index bf1b2af6ba3..4d2c31ba7c5 100644
--- a/arch/arm/src/kinetis/kinetis_pinirq.c
+++ b/arch/arm/src/kinetis/kinetis_pinirq.c
@@ -325,7 +325,7 @@ int kinetis_pinirqattach(uint32_t pinset, xcpt_t pinisr, void *arg)
 #endif
       default:
         leave_critical_section(flags);
-        return NULL;
+        return -EINVAL;
     }
 
    /* Get the old PIN ISR and set the new PIN ISR */