diff --git a/actionpack/lib/action_view/template.rb b/actionpack/lib/action_view/template.rb
index 720890eeb9..946db1df79 100644
--- a/actionpack/lib/action_view/template.rb
+++ b/actionpack/lib/action_view/template.rb
@@ -324,7 +324,8 @@ def handle_render_error(view, e) #:nodoc:
       end
 
       def locals_code #:nodoc:
-        @locals.map { |key| "#{key} = local_assigns[:#{key}];" }.join
+        # Double assign to suppress the dreaded 'assigned but unused variable' warning
+        @locals.map { |key| "#{key} = #{key} = local_assigns[:#{key}];" }.join
       end
 
       def method_name #:nodoc:
diff --git a/actionpack/test/controller/test_case_test.rb b/actionpack/test/controller/test_case_test.rb
index 9c6d02a62d..38b9794b4d 100644
--- a/actionpack/test/controller/test_case_test.rb
+++ b/actionpack/test/controller/test_case_test.rb
@@ -58,7 +58,7 @@ def test_protocol
     end
 
     def test_headers
-      render text: JSON.dump(request.headers.env)
+      render text: request.headers.env.to_json
     end
 
     def test_html_output