diff --git a/arch/arm/src/stm32f7/stm32_flash.c b/arch/arm/src/stm32f7/stm32_flash.c
index 6268ecff6be..2b8fdbc8c02 100644
--- a/arch/arm/src/stm32f7/stm32_flash.c
+++ b/arch/arm/src/stm32f7/stm32_flash.c
@@ -138,7 +138,7 @@ int stm32_flash_unlock(void)
   return ret;
 }
 
-void stm32_flash_lock(void)
+int stm32_flash_lock(void)
 {
   int ret;