diff --git a/xpath.c b/xpath.c
old mode 100644
new mode 100755
index 65a9f09e..9cbd6650
--- a/xpath.c
+++ b/xpath.c
@@ -8626,6 +8626,7 @@ xmlXPathIdFunction(xmlXPathParserContextPtr ctxt, int nargs) {
 	return;
     }
     obj = xmlXPathCacheConvertString(ctxt->context, obj);
+    if (obj == NULL) return;
     ret = xmlXPathGetElementsByIds(ctxt->context->doc, obj->stringval);
     valuePush(ctxt, xmlXPathCacheWrapNodeSet(ctxt->context, ret));
     xmlXPathReleaseObject(ctxt->context, obj);