diff --git a/rdf/datasource/src/nsXULContentSink.cpp b/rdf/datasource/src/nsXULContentSink.cpp
index 711836afd908..efdeea9df50c 100644
--- a/rdf/datasource/src/nsXULContentSink.cpp
+++ b/rdf/datasource/src/nsXULContentSink.cpp
@@ -1025,6 +1025,22 @@ XULContentSinkImpl::AddAttributes(const nsIParserNode& aNode,
         v = aNode.GetValueAt(i);
         nsRDFParserUtils::StripAndConvert(v);
 
+#define USE_TAG_NAMESPACE_AS_DEFAULT_NAMESPACE
+#ifdef  USE_TAG_NAMESPACE_AS_DEFAULT_NAMESPACE
+        // XXX This is a hack that I'm not sure is legal: as a last
+        // ditch effort, we treat attributes with an unknown (or no)
+        // namespace as being in the same namespace as the tag itself.
+        if ((nameSpaceID == kNameSpaceID_Unknown) ||
+            (nameSpaceID == kNameSpaceID_None)) {
+            nsAutoString tag = aNode.GetText();
+            nsIAtom* prefix = CutNameSpacePrefix(tag);
+            if (prefix) {
+                nameSpaceID = GetNameSpaceID(prefix);
+                NS_RELEASE(prefix);
+            }
+        }
+#endif
+
         // Get the URI for the namespace, so we can construct a
         // fully-qualified property name.
         mNameSpaceManager->GetNameSpaceURI(nameSpaceID, k);