diff -r fe532dccf8f6 Lib/test/test_minidom.py
--- a/Lib/test/test_minidom.py	Mon Apr 14 10:30:43 2014 -0400
+++ b/Lib/test/test_minidom.py	Mon Apr 14 11:37:26 2014 -0400
@@ -1518,6 +1518,10 @@
         doc2 = parseString(doc.toxml())
         self.confirm(doc2.namespaceURI == xml.dom.EMPTY_NAMESPACE)
 
+    def testExceptionOnSpacesInXMLNSValue(self):
+        with self.assertRaisesRegexp(ValueError, 'Invalid syntax'):
+            parseString('<element xmlns:abc="http:abc.com/de f g/hi/j k"><abc:foo /></element>')
+
     def testDocRemoveChild(self):
         doc = parse(tstfile)
         title_tag = doc.documentElement.getElementsByTagName("TITLE")[0]
diff -r fe532dccf8f6 Lib/xml/dom/expatbuilder.py
--- a/Lib/xml/dom/expatbuilder.py	Mon Apr 14 10:30:43 2014 -0400
+++ b/Lib/xml/dom/expatbuilder.py	Mon Apr 14 11:37:26 2014 -0400
@@ -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