diff --git a/Makefile.win b/Makefile.win
index 5498ad9af2..1ac8a22e6b 100644
--- a/Makefile.win
+++ b/Makefile.win
@@ -402,6 +402,9 @@ A
 <<
 	xcopy include\*.h "$(INSTDIR)\include" /d < <<
 A
+<<
+	xcopy os\win32\*.h "$(INSTDIR)\include" /d < <<
+A
 <<
         xcopy docs\icons "$(INSTDIR)\icons" /s /d < <<
 A