Index: src/org/python/core/PyDictionary.java
===================================================================
--- src/org/python/core/PyDictionary.java	(revision 7169)
+++ src/org/python/core/PyDictionary.java	(working copy)
@@ -599,13 +599,14 @@
 
     @ExposedMethod(defaults = "null", doc = BuiltinDocs.dict_pop_doc)
     final PyObject dict_pop(PyObject key, PyObject defaultValue) {
-        if (!map.containsKey(key)) {
+        ConcurrentMap<PyObject, PyObject> m = getMap();
+        if (!m.containsKey(key)) {
             if (defaultValue == null) {
                 throw Py.KeyError("popitem(): dictionary is empty");
             }
             return defaultValue;
         }
-        return getMap().remove(key);
+        return m.remove(key);
     }