Index: src/formats/xml/xml.cpp
--- src/formats/xml/xml.cpp.orig
+++ src/formats/xml/xml.cpp
@@ -143,7 +143,7 @@ namespace OpenBabel
             pxmlConv->pInFormat = pConv->GetInFormat();
 
             if(xmlReaderNewIO( pxmlConv->_reader, ReadStream, NULL, pxmlConv, "", NULL, 0)==-1)
-              return false;
+              return NULL;
           }
       }
     else
