diff --git a/activerecord/lib/active_record/enum.rb b/activerecord/lib/active_record/enum.rb
index 167f8b7a493c4..6e0d19ad31241 100644
--- a/activerecord/lib/active_record/enum.rb
+++ b/activerecord/lib/active_record/enum.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/object/deep_dup'
+
 module ActiveRecord
   # Declare an enum attribute where the values map to integers in the database,
   # but can be queried by name. Example:
@@ -70,8 +72,9 @@ def self.extended(base)
       base.defined_enums = {}
     end
 
-    def enum_mapping_for(attr_name) # :nodoc:
-      defined_enums[attr_name.to_s]
+    def inherited(base)
+      base.defined_enums = defined_enums.deep_dup
+      super
     end
 
     def enum(definitions)
@@ -136,7 +139,7 @@ def _enum_methods_module
           mod = Module.new do
             private
               def save_changed_attribute(attr_name, value)
-                if (mapping = self.class.enum_mapping_for(attr_name))
+                if (mapping = self.class.defined_enums[attr_name])
                   if attribute_changed?(attr_name)
                     old = changed_attributes[attr_name]
 
diff --git a/activerecord/lib/active_record/validations/uniqueness.rb b/activerecord/lib/active_record/validations/uniqueness.rb
index 71c71cb4b1b6a..ee080451a924c 100644
--- a/activerecord/lib/active_record/validations/uniqueness.rb
+++ b/activerecord/lib/active_record/validations/uniqueness.rb
@@ -93,7 +93,7 @@ def deserialize_attribute(record, attribute, value)
       end
 
       def map_enum_attribute(klass, attribute, value)
-        mapping = klass.enum_mapping_for(attribute.to_s)
+        mapping = klass.defined_enums[attribute.to_s]
         value = mapping[value] if value && mapping
         value
       end
diff --git a/activerecord/test/cases/enum_test.rb b/activerecord/test/cases/enum_test.rb
index 5157c272ca252..3b2f0dfe07023 100644
--- a/activerecord/test/cases/enum_test.rb
+++ b/activerecord/test/cases/enum_test.rb
@@ -252,17 +252,38 @@ def self.name; 'Book'; end
   end
 
   test "enums are distinct per class" do
-    Plane = Class.new(ActiveRecord::Base) do
-      enum status: [:grounded, :operational]
+    klass1 = Class.new(ActiveRecord::Base) do
+      self.table_name = "books"
+      enum status: [:proposed, :written]
+    end
+
+    klass2 = Class.new(ActiveRecord::Base) do
+      self.table_name = "books"
+      enum status: [:drafted, :uploaded]
     end
-    assert_equal({ "proposed" => 0, "written" => 1, "published" => 2 }, Book.statuses)
-    assert_equal({ "grounded" => 0, "operational" => 1 }, Plane.statuses)
+
+    book1 = klass1.proposed.create!
+    book1.status = :written
+    assert_equal ['proposed', 'written'], book1.status_change
+
+    book2 = klass2.drafted.create!
+    book2.status = :uploaded
+    assert_equal ['drafted', 'uploaded'], book2.status_change
   end
 
   test "enums are inheritable" do
-    Encyclopedia = Class.new(Book) do
-      enum status: [:published, :reprinted]
+    subklass1 = Class.new(Book)
+
+    subklass2 = Class.new(Book) do
+      enum status: [:drafted, :uploaded]
     end
-    assert_equal({ "published" => 0, "reprinted" => 1 }, Encyclopedia.statuses)
+
+    book1 = subklass1.proposed.create!
+    book1.status = :written
+    assert_equal ['proposed', 'written'], book1.status_change
+
+    book2 = subklass2.drafted.create!
+    book2.status = :uploaded
+    assert_equal ['drafted', 'uploaded'], book2.status_change
   end
 end