diff --git a/src/if_python3.c b/src/if_python3.c
index 28820ae..cae18c2 100644
--- a/src/if_python3.c
+++ b/src/if_python3.c
@@ -1519,6 +1519,7 @@
     /* The special value is removed from sys.path in Python3_Init(). */
     static wchar_t *(argv[2]) = {L"/must>not&exist/foo", NULL};
 
+    PyType_Ready(&IterType);
     PyType_Ready(&BufferType);
     PyType_Ready(&RangeType);
     PyType_Ready(&WindowType);