diff --git a/Lib/xml/dom/expatbuilder.py b/Lib/xml/dom/expatbuilder.py
--- a/Lib/xml/dom/expatbuilder.py
+++ b/Lib/xml/dom/expatbuilder.py
@@ -121,10 +121,12 @@
         qname = "%s:%s" % (prefix, localname)
         qname = intern(qname, qname)
         localname = intern(localname, localname)
-    else:
+    elif len(parts) == 2:
         uri, localname = parts
         prefix = EMPTY_PREFIX
         qname = localname = intern(localname, localname)
+    else:
+        raise ValueError("Invalid syntax in name: '" + name + "'")
     return intern(uri, uri), localname, prefix, qname