diff --git a/reactos/include/psdk/winddi.h b/reactos/include/psdk/winddi.h
index 7bdc31011cb..4346cbdf701 100644
--- a/reactos/include/psdk/winddi.h
+++ b/reactos/include/psdk/winddi.h
@@ -4345,7 +4345,7 @@ typedef BOOL
     _In_ HANDLE   hLogicalSurface,
     _In_ SIZEL    sizl);
 typedef FN_DrvAssociateSharedSurface *PFN_DrvAssociateSharedSurface;
-extern
+extern FN_DrvAssociateSharedSurface DrvAssociateSharedSurface;
 
 typedef LONG
 (APIENTRY FN_DrvSynchronizeRedirectionBitmaps)(