diff --git a/reactos/include/win32k/region.h b/reactos/include/win32k/region.h
index 5103346b8b1..406b4e94a06 100644
--- a/reactos/include/win32k/region.h
+++ b/reactos/include/win32k/region.h
@@ -143,5 +143,6 @@ STDCALL
 W32kGetRegionData(HRGN hrgn,
 						DWORD count,
 						LPRGNDATA rgndata);
+HRGN REGION_CropRgn(HRGN hDst, HRGN hSrc, const PRECT lpRect, PPOINT lpPt);
 #endif