d is the correct format string
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index 82bfb14..d6dcffd 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -670,7 +670,7 @@
return NULL;
}
if (((dequeobject *)deque)->maxlen != -1)
- fmt = PyString_FromFormat("deque(%%r, maxlen=%" PY_FORMAT_SIZE_T "i)",
+ fmt = PyString_FromFormat("deque(%%r, maxlen=%" PY_FORMAT_SIZE_T "d)",
((dequeobject *)deque)->maxlen);
else
fmt = PyString_FromString("deque(%r)");