diff -r 864b9836dae6 Objects/stringobject.c
--- a/Objects/stringobject.c	Fri Jan 25 17:55:39 2013 +0100
+++ b/Objects/stringobject.c	Fri Jan 25 22:12:33 2013 +0200
@@ -10,8 +10,8 @@
 Py_ssize_t null_strings, one_strings;
 #endif
 
-static PyStringObject *characters[UCHAR_MAX + 1];
-static PyStringObject *nullstring;
+static PyStringObject *characters[UCHAR_MAX + 1] = {NULL};
+static PyStringObject *nullstring = NULL;
 
 /* This dictionary holds all interned strings.  Note that references to
    strings in this dictionary are *not* counted in the string's ob_refcnt.
@@ -21,7 +21,7 @@
    Another way to look at this is that to say that the actual reference
    count of a string is:  s->ob_refcnt + (s->ob_sstate?2:0)
 */
-static PyObject *interned;
+static PyObject *interned = NULL;
 
 /* PyStringObject_SIZE gives the basic size of a string; any memory allocation
    for a string of length n should request PyStringObject_SIZE + n bytes.
@@ -4786,12 +4786,9 @@
 PyString_Fini(void)
 {
     int i;
-    for (i = 0; i < UCHAR_MAX + 1; i++) {
-        Py_XDECREF(characters[i]);
-        characters[i] = NULL;
-    }
-    Py_XDECREF(nullstring);
-    nullstring = NULL;
+    for (i = 0; i < UCHAR_MAX + 1; i++)
+        Py_CLEAR(characters[i]);
+    Py_CLEAR(nullstring);
 }
 
 void _Py_ReleaseInternedStrings(void)
@@ -4841,6 +4838,5 @@
                     "mortal/immortal\n", mortal_size, immortal_size);
     Py_DECREF(keys);
     PyDict_Clear(interned);
-    Py_DECREF(interned);
-    interned = NULL;
+    Py_CLEAR(interned);
 }