diff --git a/test/engine_test.rb b/test/engine_test.rb
index 29681d7a..e67ab5d7 100644
--- a/test/engine_test.rb
+++ b/test/engine_test.rb
@@ -310,5 +310,14 @@ def test_import_plain_css
       output = Engine.new("@import 'test'").render
       assert_equal expected_output, output
     end
+
+    def test_color_functions
+      expected_output = <<-CSS
+a {
+  color: #aabbcc; }
+  CSS
+      output = Engine.new('a { color: lighten(#abc, 0%); }').render
+      assert_equal expected_output, output
+    end
   end
 end