diff --git a/Modules/_testcapi/module.c b/Modules/_testcapi/module.c
index 7b5861bc08ed77..ef657842e77494 100644
--- a/Modules/_testcapi/module.c
+++ b/Modules/_testcapi/module.c
@@ -178,7 +178,7 @@ module_from_slots_exec(PyObject *self, PyObject *spec)
 }
 
 static PyObject *
-create_attr_from_spec(PyObject *spec, PyObject *def)
+create_attr_from_spec(PyObject *spec, PyModuleDef *def)
 {
     assert(!def);
     return PyObject_GetAttrString(spec, "_gimme_this");