1 files changed, 4 insertions, 2 deletions
diff --git a/activesupport/lib/active_support/json/encoders/core.rb b/activesupport/lib/active_support/json/encoders/core.rb
index d8571be9c8..f6cdfbcde5 100644
--- a/activesupport/lib/active_support/json/encoders/core.rb
+++ b/activesupport/lib/active_support/json/encoders/core.rb
@@ -51,8 +51,10 @@ module ActiveSupport
       
       define_encoder Hash do |hash|
         returning result = '{' do
-          result << hash.map do |pair|
-            pair.map { |value| value.to_json } * ': '
+          result << hash.map do |key, value|
+            key = ActiveSupport::JSON::Variable.new(key.to_s) if 
+              ActiveSupport::JSON.can_unquote_identifier?(key)
+            "#{key.to_json}: #{value.to_json}"
           end * ', '
           result << '}'
         end