Index: Lib/xml/etree/ElementTree.py
===================================================================
--- Lib/xml/etree/ElementTree.py	(revision 64415)
+++ Lib/xml/etree/ElementTree.py	(working copy)
@@ -834,7 +834,7 @@
     # tag and namespace declaration, if any
     if isinstance(tag, QName):
         tag = tag.text
-    namespace_uri, tag = string.split(tag[1:], "}", 1)
+    namespace_uri, tag = string.rsplit(tag[1:], "}", 1)
     prefix = namespaces.get(namespace_uri)
     if prefix is None:
         prefix = _namespace_map.get(namespace_uri)
Index: Lib/test/test_xml_etree.py
===================================================================
--- Lib/test/test_xml_etree.py	(revision 64415)
+++ Lib/test/test_xml_etree.py	(working copy)
@@ -200,7 +200,18 @@
     'body'
     """
 
+def parse_namespace():
+    """
+    >>> from xml.etree import ElementTree as ET
+    >>> e = ET.XML('<prefix:localname xmlns:prefix="${stuff}"/>')
+    >>> e.tag
+    '{${stuff}}localname'
+    >>> t = ET.ElementTree(e)
+    >>> ET.tostring(e)
+    '<ns0:localname xmlns:ns0="${stuff}" />'
+    """
 
+
 def check_encoding(ET, encoding):
     """
     >>> from xml.etree import ElementTree as ET