diff --git a/Modules/_xxsubinterpretersmodule.c b/Modules/_xxsubinterpretersmodule.c
index ed79a13..d2b5f26 100644
--- a/Modules/_xxsubinterpretersmodule.c
+++ b/Modules/_xxsubinterpretersmodule.c
@@ -1916,7 +1916,7 @@
 channel_drop_interpreter(PyObject *self, PyObject *args, PyObject *kwds)
 {
     // Note that only the current interpreter is affected.
-    static char *kwlist[] = {"id", "send", "recv"};
+    static char *kwlist[] = {"id", "send", "recv", NULL};
     PyObject *id;
     int send = -1;
     int recv = -1;