diff --git a/Objects/stringlib/join.h b/Objects/stringlib/join.h
index 4d023ed1a8..8ad598ad5c 100644
--- a/Objects/stringlib/join.h
+++ b/Objects/stringlib/join.h
@@ -20,7 +20,7 @@ STRINGLIB(bytes_join)(PyObject *sep, PyObject *iterable)
     Py_buffer static_buffers[NB_STATIC_BUFFERS];
 #define GIL_THRESHOLD 1048576
     int drop_gil = 1;
-    PyThreadState *save;
+    PyThreadState *save = NULL;
 
     seq = PySequence_Fast(iterable, "can only join an iterable");
     if (seq == NULL) {