diff --git a/activesupport/lib/active_support/json/encoders/date_time.rb b/activesupport/lib/active_support/json/encoders/date_time.rb
index d41c3e9786a06..a4a5efbfb1576 100644
--- a/activesupport/lib/active_support/json/encoders/date_time.rb
+++ b/activesupport/lib/active_support/json/encoders/date_time.rb
@@ -8,7 +8,7 @@ def to_json(options = nil)
     if ActiveSupport.use_standard_json_time_format
       xmlschema.inspect
     else
-      %("#{strftime("%Y/%m/%d %H:%M:%S %z")}")
+      strftime('"%Y/%m/%d %H:%M:%S %z"')
     end
   end
 end