diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py
index e55d10b..3e9c8b5 100644
--- a/Lib/test/test_ast.py
+++ b/Lib/test/test_ast.py
@@ -402,6 +402,15 @@
         self.assertRaises(TypeError, ast.Num, 1, None, 2)
         self.assertRaises(TypeError, ast.Num, 1, None, 2, lineno=0)
 
+        # Arbitrary keyword arguments are supported
+        self.assertEqual(ast.Constant(1, foo='bar').foo, 'bar')
+        self.assertEqual(ast.Num(1, foo='bar').foo, 'bar')
+
+        with self.assertRaisesRegex(TypeError, "Num got multiple values for argument 'n'"):
+            ast.Num(1, n=2)
+        with self.assertRaisesRegex(TypeError, "Constant got multiple values for argument 'value'"):
+            ast.Constant(1, value=2)
+
         self.assertEqual(ast.Num(42).n, 42)
         self.assertEqual(ast.Num(4.25).n, 4.25)
         self.assertEqual(ast.Num(4.25j).n, 4.25j)