diff --git a/lib/ruby-enum/enum.rb b/lib/ruby-enum/enum.rb
index 0930e86..6693b66 100644
--- a/lib/ruby-enum/enum.rb
+++ b/lib/ruby-enum/enum.rb
@@ -19,6 +19,9 @@ def self.included(base)
       base.extend ClassMethods
 
       base.private_class_method(:new)
+
+      base.instance_variable_set(:@_enum_hash, {})
+      base.instance_variable_set(:@_enums_by_value, {})
     end
 
     module ClassMethods
diff --git a/spec/ruby-enum/enum_spec.rb b/spec/ruby-enum/enum_spec.rb
index a3d811e..8c32b6a 100644
--- a/spec/ruby-enum/enum_spec.rb
+++ b/spec/ruby-enum/enum_spec.rb
@@ -17,6 +17,13 @@ class FirstSubclass < Colors
   class SecondSubclass < FirstSubclass
     define :PINK, 'pink'
   end
+
+  class OtherSecondSubclass < FirstSubclass
+    include Ruby::Enum
+
+    define :MAGENTA, 'magenta'
+  end
+
   it 'returns an enum value' do
     expect(Colors::RED).to eq 'red'
     expect(Colors::GREEN).to eq 'green'
@@ -169,6 +176,12 @@ class SecondSubclass < FirstSubclass
         expect(SecondSubclass.values).to eq(%w[red green orange pink])
       end
     end
+
+    context 'when a subclass of a subclass is defined with redundant module inclusion' do
+      it 'returns all values' do
+        expect(OtherSecondSubclass.values).to eq(%w[red green orange magenta])
+      end
+    end
   end
 
   describe '#to_h' do
@@ -229,6 +242,22 @@ class SecondSubclass < FirstSubclass
     end
   end
 
+  # rubocop:disable Rspec/DescribedClass
+  describe 'Reloading enum definition' do
+    it 'plays nice with lazy loading in Ruby on Rails' do
+      class_body = proc do
+        include Ruby::Enum
+
+        define :BALD, 'bald'
+      end
+
+      HairStyles = Class.new(&class_body)
+
+      expect { HairStyles.class_eval(&class_body) }.not_to raise_error
+    end
+  end
+  # rubocop:enable Rspec/DescribedClass
+
   describe 'Given a class that has not defined any enums' do
     class EmptyEnums
       include Ruby::Enum