diff --git a/middleclass.lua b/middleclass.lua
index 88634c2..d9c37e2 100644
--- a/middleclass.lua
+++ b/middleclass.lua
@@ -109,7 +109,7 @@ local function _setClassMetatable(aClass)
 end
 
 local function _createClass(name, super)
-  local aClass = { name = name, super = super, static = {}, __mixins = {}, __instanceDict = {}, __instanceMeta = {} }
+  local aClass = { name = name, super = super, static = {}, __instanceDict = {}, __instanceMeta = {} }
   aClass.subclasses = setmetatable({}, {__mode = "k"})
 
   _setClassDictionariesMetatables(aClass)
@@ -141,7 +141,6 @@ local function _includeMixin(aClass, mixin)
     end
   end
   if type(mixin.included)=="function" then mixin:included(aClass) end
-  aClass.__mixins[mixin] = true
 end
 
 local Object = {
@@ -199,17 +198,6 @@ local Object = {
       assert(type(self) == 'table', "Make sure you that you are using 'Class:include' instead of 'Class.include'")
       for _,mixin in ipairs({...}) do _includeMixin(self, mixin) end
       return self
-    end,
-
-    includes = function(self, mixin)
-      return type(mixin)          == 'table' and
-             type(self)           == 'table' and
-             type(self.__mixins)  == 'table' and
-             ( self.__mixins[mixin] or
-               type(self.super)           == 'table' and
-               type(self.super.includes)  == 'function' and
-               self.super:includes(mixin)
-             )
     end
   }
 }
diff --git a/spec/default_methods_spec.lua b/spec/default_methods_spec.lua
index 6f12bb6..875191f 100644
--- a/spec/default_methods_spec.lua
+++ b/spec/default_methods_spec.lua
@@ -260,73 +260,6 @@ describe('Default methods', function()
 
     end)
   end)
-
-  describe('includes', function()
-
-    describe('nils, numbers, etc', function()
-      local o = Object:new()
-      local primitives = {nil, 1, 'hello', {}, function() end}
-
-      for _,primitive in pairs(primitives) do
-        local theType = type(primitive)
-        describe('A ' .. theType, function()
-
-          local f1 = function() return Object.includes(Object, primitive) end
-          local f2 = function() return Object.includes(primitive, o) end
-          local f3 = function() return Object.includes(primitive, primitive) end
-
-
-          describe('don\'t throw errors', function()
-            it('includes(Object, '.. theType ..')', function()
-              assert.not_error(f1)
-            end)
-            it('includes(' .. theType .. ', Object:new())', function()
-              assert.not_error(f2)
-            end)
-            it('includes(' .. theType .. ',' .. theType ..')', function()
-              assert.not_error(f3)
-            end)
-          end)
-
-          it('make includes return false', function()
-            assert.is_false(f1())
-            assert.is_false(f2())
-            assert.is_false(f3())
-          end)
-
-        end)
-      end -- for
-
-    end)
-
-    describe('A class', function()
-
-      local Class1 = class('Class1')
-      local Class2 = class('Class2', Class1)
-      local Class3 = class('Class3', Class2)
-      local UnrelatedClass = class('Unrelated')
-
-      local hasFoo = { foo=function() return 'foo' end }
-      Class1:include(hasFoo)
-
-      it('returns true if it includes a mixin', function()
-        assert.is_true(Class1:includes(hasFoo))
-      end)
-
-      it('returns true if its superclass includes a mixin', function()
-        assert.is_true(Class2:includes(hasFoo))
-        assert.is_true(Class3:includes(hasFoo))
-      end)
-
-      it('returns false otherwise', function()
-        assert.is_false(UnrelatedClass:includes(hasFoo))
-      end)
-
-    end)
-
-  end)
-
-
 end)