diff --git a/Python/compile.c b/Python/compile.c
index d50344c..3cf8c6e 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -379,7 +379,7 @@
         Py_DECREF(sorted_keys);
         return NULL;
     }
-    num_keys = PyList_GET_SIZE(src);
+    num_keys = PyList_GET_SIZE(sorted_keys);
 
     for (key_i = 0; key_i < num_keys; key_i++) {
         k = PyList_GET_ITEM(sorted_keys, key_i);