diff --git a/dlls/ole32/marshal.c b/dlls/ole32/marshal.c
index 01368cbd04a..4294cb5d9e3 100644
--- a/dlls/ole32/marshal.c
+++ b/dlls/ole32/marshal.c
@@ -1550,7 +1550,7 @@ HRESULT WINAPI CoMarshalInterface(IStream *pStream, REFIID riid, IUnknown *pUnk,
     dump_MSHLFLAGS(mshlFlags);
     TRACE(")\n");
 
-    if (pUnk == NULL)
+    if (!pUnk || !pStream)
         return E_INVALIDARG;
 
     objref.signature = OBJREF_SIGNATURE;