diff --git a/MdePkg/Include/Library/ArmLib.h b/MdePkg/Include/Library/ArmLib.h
index 087cddfb76..a5823afdb2 100644
--- a/MdePkg/Include/Library/ArmLib.h
+++ b/MdePkg/Include/Library/ArmLib.h
@@ -156,7 +156,7 @@ ArmInstructionCacheLineLength (
   VOID
   );
 
-UINTN
+UINT32
 EFIAPI
 ArmCacheWritebackGranule (
   VOID