diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 177b92e..7be8c9c 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -665,6 +665,9 @@
         ret, out, err = assert_python_ok(*args)
         self.assertIn(b"free PyDictObjects", err)
 
+        # The function has no parameter
+        self.assertRaises(TypeError, sys._debugmallocstats, True)
+
     @unittest.skipUnless(hasattr(sys, "getallocatedblocks"),
                          "sys.getallocatedblocks unavailable on this build")
     def test_getallocatedblocks(self):
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index d238561..cf580f1 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1186,7 +1186,7 @@
     {"settrace",        sys_settrace, METH_O, settrace_doc},
     {"gettrace",        sys_gettrace, METH_NOARGS, gettrace_doc},
     {"call_tracing", sys_call_tracing, METH_VARARGS, call_tracing_doc},
-    {"_debugmallocstats", sys_debugmallocstats, METH_VARARGS,
+    {"_debugmallocstats", sys_debugmallocstats, METH_NOARGS,
      debugmallocstats_doc},
     {NULL,              NULL}           /* sentinel */
 };