diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index b41c5de..aaac660 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -1086,7 +1086,7 @@
         }
     }
     deque->maxlen = maxlen;
-    if (Py_SIZE(deque) > 0)
+    if (deque->len > 0)
         deque_clear(deque);
     if (iterable != NULL) {
         PyObject *rv = deque_extend(deque, iterable);