diff --git a/tests/json_generator_test.rb b/tests/json_generator_test.rb
old mode 100644
new mode 100755
index b0f9a0175..f71999b12
--- a/tests/json_generator_test.rb
+++ b/tests/json_generator_test.rb
@@ -391,7 +391,7 @@ def to_s; self; end
     end
   end
 
-  if defined?(JSON::Ext::Generator)
+  if defined?(JSON::Ext::Generator) and RUBY_PLATFORM != "java"
     def test_string_ext_included_calls_super
       included = false