diff --git a/ArmPlatformPkg/Drivers/LcdGraphicsOutputDxe/LcdGraphicsOutputDxe.c b/ArmPlatformPkg/Drivers/LcdGraphicsOutputDxe/LcdGraphicsOutputDxe.c
index 55f7451708..833d1497e5 100644
--- a/ArmPlatformPkg/Drivers/LcdGraphicsOutputDxe/LcdGraphicsOutputDxe.c
+++ b/ArmPlatformPkg/Drivers/LcdGraphicsOutputDxe/LcdGraphicsOutputDxe.c
@@ -220,6 +220,7 @@ EXIT:
   and uninstall the protocols
 **/
 VOID
+EFIAPI
 LcdGraphicsExitBootServicesEvent (
   IN EFI_EVENT  Event,
   IN VOID       *Context
diff --git a/ArmPlatformPkg/Drivers/LcdGraphicsOutputDxe/LcdGraphicsOutputDxe.h b/ArmPlatformPkg/Drivers/LcdGraphicsOutputDxe/LcdGraphicsOutputDxe.h
index 1094602c0f..7a6cf6b5e0 100644
--- a/ArmPlatformPkg/Drivers/LcdGraphicsOutputDxe/LcdGraphicsOutputDxe.h
+++ b/ArmPlatformPkg/Drivers/LcdGraphicsOutputDxe/LcdGraphicsOutputDxe.h
@@ -44,6 +44,7 @@ typedef struct {
 //
 
 VOID
+EFIAPI
 LcdGraphicsExitBootServicesEvent (
   IN EFI_EVENT  Event,
   IN VOID       *Context