diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index a048507..efe5b29 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1823,7 +1823,8 @@
 PySys_HasWarnOptions(void)
 {
     PyObject *warnoptions = _PySys_GetObjectId(&PyId_warnoptions);
-    return (warnoptions != NULL && (PyList_Size(warnoptions) > 0)) ? 1 : 0;
+    return (warnoptions != NULL && PyList_Check(warnoptions)
+            && PyList_GET_SIZE(warnoptions) > 0);
 }
 
 static PyObject *