cell_compare needs to return -2 instead of NULL.
diff --git a/Objects/cellobject.c b/Objects/cellobject.c
index 37cde41..2286aaf 100644
--- a/Objects/cellobject.c
+++ b/Objects/cellobject.c
@@ -57,7 +57,7 @@
 	/* Py3K warning for comparisons  */
 	if (Py_Py3kWarningFlag && PyErr_Warn(PyExc_DeprecationWarning,
 			"cell comparisons not supported in 3.x.") < 0) {
-		return NULL;
+		return -2;
 	}
 
 	if (a->ob_ref == NULL) {