diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
index 33ae067de4b..f52297d33f2 100644
--- a/Modules/_asynciomodule.c
+++ b/Modules/_asynciomodule.c
@@ -3023,7 +3023,7 @@ _asyncio__leave_task_impl(PyObject *module, PyObject *loop, PyObject *task)
 
 
 static void
-module_free_freelists()
+module_free_freelists(void)
 {
     PyObject *next;
     PyObject *current;