diff --git a/mitogen/core.py b/mitogen/core.py
index 8b5ba63a..1cdb4428 100644
--- a/mitogen/core.py
+++ b/mitogen/core.py
@@ -504,6 +504,9 @@ class Importer(object):
             # always a negative round-trip.
             'builtins',
             '__builtin__',
+            # org.python.core imported by copy, pickle, xml.sax; breaks Jython,
+            # but very unlikely to trigger a bug report.
+            'org',
         ]
 
         # Presence of an entry in this map indicates in-flight GET_MODULE.