diff --git a/Source/Core/Common/ArmCommon.h b/Source/Core/Common/ArmCommon.h
index a18795110e..2e0b99e54c 100644
--- a/Source/Core/Common/ArmCommon.h
+++ b/Source/Core/Common/ArmCommon.h
@@ -2,6 +2,8 @@
 // Licensed under GPLv2+
 // Refer to the license.txt file included.
 
+#pragma once
+
 #include "Common/CommonTypes.h"
 
 enum CCFlags