diff --git a/test/html5/test_nokogumbo.rb b/test/html5/test_nokogumbo.rb
index e2e4d037d46..01524020fa3 100644
--- a/test/html5/test_nokogumbo.rb
+++ b/test/html5/test_nokogumbo.rb
@@ -340,6 +340,15 @@ def test_line_cdata
     assert_equal(expected, frag.at_css("div").children.map(&:type))
   end
 
+  it "raises an exception if an unexpected kwarg is provided" do
+    assert_raises(ArgumentError) do
+      Nokogiri::HTML5::Document.parse("<p>", foo: "bar")
+    end
+    assert_raises(ArgumentError) do
+      Nokogiri::HTML5::DocumentFragment.parse("<p>", Encoding::UTF_8, foo: "bar")
+    end
+  end
+
   private
 
   def buffer