diff --git a/include/ole2.h b/include/ole2.h
index 0c78e42..3651a98 100644
--- a/include/ole2.h
+++ b/include/ole2.h
@@ -106,6 +106,7 @@
 HRESULT     WINAPI CreateOleAdviseHolder (LPOLEADVISEHOLDER *ppOAHolder);
 HRESULT     WINAPI OleInitialize(LPVOID pvReserved);
 void        WINAPI OleUninitialize(void);
+BOOL        WINAPI IsValidInterface(LPUNKNOWN punk);
 
 /*
  *  OLE version conversion declarations