diff --git a/lib/devise/orm/active_record.rb b/lib/devise/orm/active_record.rb
index 4ffe1989..781c8dfe 100644
--- a/lib/devise/orm/active_record.rb
+++ b/lib/devise/orm/active_record.rb
@@ -23,7 +23,7 @@ module Devise
         include Devise::Schema
 
         # Tell how to apply schema methods.
-        def apply_schema(name, type, options={})
+        def apply_devise_schema(name, type, options={})
           column name, type.to_s.downcase.to_sym, options
         end
       end
diff --git a/lib/devise/orm/data_mapper.rb b/lib/devise/orm/data_mapper.rb
index 0de22c70..ae157976 100644
--- a/lib/devise/orm/data_mapper.rb
+++ b/lib/devise/orm/data_mapper.rb
@@ -21,7 +21,7 @@ module Devise
 
         # Tell how to apply schema methods. This automatically maps :limit to
         # :length and :null to :required.
-        def apply_schema(name, type, options={})
+        def apply_devise_schema(name, type, options={})
           SCHEMA_OPTIONS.each do |old_key, new_key|
             next unless options.key?(old_key)
             options[new_key] = options.delete(old_key)
diff --git a/lib/devise/orm/mongoid.rb b/lib/devise/orm/mongoid.rb
index 0c110208..7cb368da 100644
--- a/lib/devise/orm/mongoid.rb
+++ b/lib/devise/orm/mongoid.rb
@@ -4,32 +4,21 @@ module Devise
       module Hook
         def devise_modules_hook!
           extend Schema
-          include ::Mongoid::Timestamps
-          include Compatibility
           yield
           return unless Devise.apply_schema
           devise_modules.each { |m| send(m) if respond_to?(m, true) }
         end
       end
-      
+
       module Schema
         include Devise::Schema
 
         # Tell how to apply schema methods
-        def apply_schema(name, type, options={})
+        def apply_devise_schema(name, type, options={})
           type = Time if type == DateTime
           field name, { :type => type }.merge(options)
         end
       end
-      
-      module Compatibility
-        def save(validate = true)
-          if validate.is_a?(Hash) && validate.has_key?(:validate)
-            validate = validate[:validate]
-          end
-          super(validate)
-        end
-      end
     end
   end
 end
diff --git a/lib/devise/schema.rb b/lib/devise/schema.rb
index e82c8372..b9d58474 100644
--- a/lib/devise/schema.rb
+++ b/lib/devise/schema.rb
@@ -21,42 +21,42 @@ module Devise
         ActiveSupport::Deprecation.warn ":encryptor as option is deprecated, simply remove it."
       end
 
-      apply_schema :email,              String, :null => null, :default => default
-      apply_schema :encrypted_password, String, :null => null, :default => default, :limit => 128
-      apply_schema :password_salt,      String, :null => null, :default => default
+      apply_devise_schema :email,              String, :null => null, :default => default
+      apply_devise_schema :encrypted_password, String, :null => null, :default => default, :limit => 128
+      apply_devise_schema :password_salt,      String, :null => null, :default => default
     end      
 
     # Creates authentication_token.
     def token_authenticatable(options={})
-      apply_schema :authentication_token, String
+      apply_devise_schema :authentication_token, String
     end
 
     # Creates confirmation_token, confirmed_at and confirmation_sent_at.
     def confirmable
-      apply_schema :confirmation_token,   String
-      apply_schema :confirmed_at,         DateTime
-      apply_schema :confirmation_sent_at, DateTime
+      apply_devise_schema :confirmation_token,   String
+      apply_devise_schema :confirmed_at,         DateTime
+      apply_devise_schema :confirmation_sent_at, DateTime
     end
 
     # Creates reset_password_token.
     def recoverable
-      apply_schema :reset_password_token, String
+      apply_devise_schema :reset_password_token, String
     end
 
     # Creates remember_token and remember_created_at.
     def rememberable
-      apply_schema :remember_token,      String
-      apply_schema :remember_created_at, DateTime
+      apply_devise_schema :remember_token,      String
+      apply_devise_schema :remember_created_at, DateTime
     end
 
     # Creates sign_in_count, current_sign_in_at, last_sign_in_at,
     # current_sign_in_ip, last_sign_in_ip.
     def trackable
-      apply_schema :sign_in_count,      Integer, :default => 0
-      apply_schema :current_sign_in_at, DateTime
-      apply_schema :last_sign_in_at,    DateTime
-      apply_schema :current_sign_in_ip, String
-      apply_schema :last_sign_in_ip,    String
+      apply_devise_schema :sign_in_count,      Integer, :default => 0
+      apply_devise_schema :current_sign_in_at, DateTime
+      apply_devise_schema :last_sign_in_at,    DateTime
+      apply_devise_schema :current_sign_in_ip, String
+      apply_devise_schema :last_sign_in_ip,    String
     end
 
     # Creates failed_attempts, unlock_token and locked_at depending on the options given.
@@ -75,18 +75,18 @@ module Devise
       lock_strategy ||= :failed_attempts
 
       if lock_strategy == :failed_attempts
-        apply_schema :failed_attempts, Integer, :default => 0
+        apply_devise_schema :failed_attempts, Integer, :default => 0
       end
 
       if [:both, :email].include?(unlock_strategy)
-        apply_schema :unlock_token, String
+        apply_devise_schema :unlock_token, String
       end
 
-      apply_schema :locked_at, DateTime
+      apply_devise_schema :locked_at, DateTime
     end
 
     # Overwrite with specific modification to create your own schema.
-    def apply_schema(name, type, options={})
+    def apply_devise_schema(name, type, options={})
       raise NotImplementedError
     end
   end
diff --git a/test/integration/database_authenticatable_test.rb b/test/integration/database_authenticatable_test.rb
index 4ace5474..3641ca5d 100644
--- a/test/integration/database_authenticatable_test.rb
+++ b/test/integration/database_authenticatable_test.rb
@@ -309,4 +309,13 @@ class AuthenticationTest < ActionController::IntegrationTest
       get '/sign_in'
     end
   end
+
+  # Invalid session
+  test 'invalid session does not cause errors' do
+    get "/"
+    session["warden.user.user.key"] = 170410
+
+    get users_path
+    assert_equal 302, response.status
+  end
 end
diff --git a/test/rails_app/app/mongoid/admin.rb b/test/rails_app/app/mongoid/admin.rb
index 083d7f2e..2fd0f10b 100644
--- a/test/rails_app/app/mongoid/admin.rb
+++ b/test/rails_app/app/mongoid/admin.rb
@@ -1,15 +1,6 @@
 class Admin
   include Mongoid::Document
+  include Shim
 
   devise :database_authenticatable, :timeoutable, :registerable, :recoverable
-  
-  def self.last(options={})
-    options.delete(:order) if options[:order] == "id"
-    super options
-  end
-  
-  # overwrite equality (because some devise tests use this for asserting model equality) 
-  def ==(other)
-    other.is_a?(self.class) && _id == other._id
-  end
 end
diff --git a/test/rails_app/app/mongoid/shim.rb b/test/rails_app/app/mongoid/shim.rb
new file mode 100644
index 00000000..fb01ec0d
--- /dev/null
+++ b/test/rails_app/app/mongoid/shim.rb
@@ -0,0 +1,16 @@
+module Shim
+  extend ::ActiveSupport::Concern
+  include ::Mongoid::Timestamps
+
+  module ClassMethods
+    def last(options={})
+      options.delete(:order) if options[:order] == "id"
+      super(options)
+    end
+  end
+  
+  # overwrite equality (because some devise tests use this for asserting model equality) 
+  def ==(other)
+    other.is_a?(self.class) && _id == other._id
+  end
+end
diff --git a/test/rails_app/app/mongoid/user.rb b/test/rails_app/app/mongoid/user.rb
index db622b7b..a133f459 100644
--- a/test/rails_app/app/mongoid/user.rb
+++ b/test/rails_app/app/mongoid/user.rb
@@ -1,21 +1,10 @@
 class User
   include Mongoid::Document
+  include Shim
 
   field :created_at, :type => DateTime
 
   devise :database_authenticatable, :confirmable, :lockable, :recoverable,
          :registerable, :rememberable, :timeoutable, :token_authenticatable,
          :trackable, :validatable
-
-  # attr_accessible :username, :email, :password, :password_confirmation
-  
-  def self.last(options={})
-    options.delete(:order) if options[:order] == "id"
-    super options
-  end
-  
-  # overwrite equality (because some devise tests use this for asserting model equality) 
-  def ==(other)
-    other.is_a?(self.class) && _id == other._id
-  end
 end