diff --git a/shell_integration/windows/OCOverlays/OCOverlayFactory.h b/shell_integration/windows/OCOverlays/OCOverlayFactory.h
index 364baa2c7c..49d859d0bd 100644
--- a/shell_integration/windows/OCOverlays/OCOverlayFactory.h
+++ b/shell_integration/windows/OCOverlays/OCOverlayFactory.h
@@ -12,11 +12,10 @@
  * details.
  */
 
-#ifndef OCOVERLAYFACTORY_H
-#define OCOVERLAYFACTORY_H
-
 #pragma once
 
+#include <unknwn.h>
+
 enum State {
     State_Error = 0,
     State_OK, State_OKShared,
@@ -43,4 +42,3 @@ private:
     int _state;
 };
 
-#endif
\ No newline at end of file
diff --git a/shell_integration/windows/OCOverlays/OCOverlayRegistrationHandler.cpp b/shell_integration/windows/OCOverlays/OCOverlayRegistrationHandler.cpp
index 7badf0f92f..e830091c70 100644
--- a/shell_integration/windows/OCOverlays/OCOverlayRegistrationHandler.cpp
+++ b/shell_integration/windows/OCOverlays/OCOverlayRegistrationHandler.cpp
@@ -16,6 +16,7 @@
 #include "OverlayConstants.h"
 
 #include <windows.h>
+#include <objbase.h>
 #include <iostream>
 #include <fstream>