diff --git a/reactos/include/ddk/winddi.h b/reactos/include/ddk/winddi.h
index 9b68a0cc734..258345da5cf 100644
--- a/reactos/include/ddk/winddi.h
+++ b/reactos/include/ddk/winddi.h
@@ -978,9 +978,8 @@ PVOID  APIENTRY  EngAllocMem(ULONG  Flags,
                              ULONG  MemSize,
                              ULONG  Tag);
 
-/*
-EngAllocUserMem
-*/
+PVOID STDCALL EngAllocUserMem(ULONG cj,
+                              ULONG tag);
 
 BOOL EngAssociateSurface(IN HSURF  Surface,
                          IN HDEV  Dev,