1 files changed, 6 insertions, 3 deletions
diff --git a/activerecord/lib/active_record/store.rb b/activerecord/lib/active_record/store.rb
index d13491502e..d836acf18f 100644
--- a/activerecord/lib/active_record/store.rb
+++ b/activerecord/lib/active_record/store.rb
@@ -43,7 +43,7 @@ module ActiveRecord
     extend ActiveSupport::Concern
 
     included do
-      class_attribute :stored_attributes
+      class_attribute :stored_attributes, instance_writer: false
       self.stored_attributes = {}
     end
 
@@ -58,8 +58,11 @@ module ActiveRecord
         keys.each do |key|
           define_method("#{key}=") do |value|
             initialize_store_attribute(store_attribute)
-            send(store_attribute)[key] = value
-            send :"#{store_attribute}_will_change!"
+            attribute = send(store_attribute)
+            if value != attribute[key]
+              attribute[key] = value
+              send :"#{store_attribute}_will_change!"
+            end
           end
 
           define_method(key) do