diff --git a/Gemfile b/Gemfile
index 7196e4c1..7cf9f1c3 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,9 +3,10 @@ source :rubygems
 gemspec
 
 gem 'country_select'
-gem 'railties', '~> 3.2.0'
-gem 'activemodel', '~> 3.2.0'
-gem 'actionpack', '~> 3.2.0'
+gem 'railties', '>= 4.0.0.beta', '< 4.1', github: 'rails/rails', branch: 'master'
+gem 'activemodel', '>= 4.0.0.beta', '< 4.1', github: 'rails/rails', branch: 'master'
+gem 'actionpack', '>= 4.0.0.beta', '< 4.1', github: 'rails/rails', branch: 'master'
+gem 'journey', github: 'rails/journey'
 gem 'rake'
 gem 'rdoc'
 gem 'mocha', :require => false
diff --git a/Gemfile.lock b/Gemfile.lock
index 5095f327..b07739a6 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,75 +1,75 @@
+GIT
+  remote: git://github.com/rails/journey.git
+  revision: 5e14f7477b3d05595bf950b33812793da2c3913c
+  specs:
+    journey (2.0.0.20120723141804)
+
+GIT
+  remote: git://github.com/rails/rails.git
+  revision: ae68fc3864e99ab43c18fd12577744e1583f6b64
+  branch: master
+  specs:
+    actionpack (4.0.0.beta)
+      activesupport (= 4.0.0.beta)
+      builder (~> 3.1.0)
+      erubis (~> 2.7.0)
+      journey (~> 2.0.0)
+      rack (~> 1.4.1)
+      rack-test (~> 0.6.1)
+    activemodel (4.0.0.beta)
+      activesupport (= 4.0.0.beta)
+      builder (~> 3.1.0)
+    activesupport (4.0.0.beta)
+      i18n (~> 0.6)
+      minitest (~> 4.1)
+      multi_json (~> 1.3)
+      tzinfo (~> 0.3.33)
+    railties (4.0.0.beta)
+      actionpack (= 4.0.0.beta)
+      activesupport (= 4.0.0.beta)
+      rake (>= 0.8.7)
+      rdoc (~> 3.4)
+      thor (>= 0.15.4, < 2.0)
+
 PATH
   remote: .
   specs:
     simple_form (3.0.0.dev)
-      actionpack (~> 3.0)
-      activemodel (~> 3.0)
+      actionpack (>= 4.0.0.beta, < 4.1)
+      activemodel (>= 4.0.0.beta, < 4.1)
 
 GEM
   remote: http://rubygems.org/
   specs:
-    actionpack (3.2.9)
-      activemodel (= 3.2.9)
-      activesupport (= 3.2.9)
-      builder (~> 3.0.0)
-      erubis (~> 2.7.0)
-      journey (~> 1.0.4)
-      rack (~> 1.4.0)
-      rack-cache (~> 1.2)
-      rack-test (~> 0.6.1)
-      sprockets (~> 2.2.1)
-    activemodel (3.2.9)
-      activesupport (= 3.2.9)
-      builder (~> 3.0.0)
-    activesupport (3.2.9)
-      i18n (~> 0.6)
-      multi_json (~> 1.0)
-    builder (3.0.4)
+    builder (3.1.4)
     country_select (1.0.1)
     erubis (2.7.0)
-    hike (1.2.1)
     i18n (0.6.1)
-    journey (1.0.4)
     json (1.7.5)
     metaclass (0.0.1)
+    minitest (4.3.3)
     mocha (0.13.0)
       metaclass (~> 0.0.1)
-    multi_json (1.3.7)
+    multi_json (1.5.0)
     rack (1.4.1)
-    rack-cache (1.2)
-      rack (>= 0.4)
-    rack-ssl (1.3.2)
-      rack
     rack-test (0.6.2)
       rack (>= 1.0)
-    railties (3.2.9)
-      actionpack (= 3.2.9)
-      activesupport (= 3.2.9)
-      rack-ssl (~> 1.3.2)
-      rake (>= 0.8.7)
-      rdoc (~> 3.4)
-      thor (>= 0.14.6, < 2.0)
     rake (10.0.1)
     rdoc (3.12)
       json (~> 1.4)
-    sprockets (2.2.1)
-      hike (~> 1.2)
-      multi_json (~> 1.0)
-      rack (~> 1.0)
-      tilt (~> 1.1, != 1.3.0)
     thor (0.16.0)
-    tilt (1.3.3)
     tzinfo (0.3.35)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  actionpack (~> 3.2.0)
-  activemodel (~> 3.2.0)
+  actionpack (>= 4.0.0.beta, < 4.1)!
+  activemodel (>= 4.0.0.beta, < 4.1)!
   country_select
+  journey!
   mocha
-  railties (~> 3.2.0)
+  railties (>= 4.0.0.beta, < 4.1)!
   rake
   rdoc
   simple_form!
diff --git a/simple_form.gemspec b/simple_form.gemspec
index e762aa76..623cb6d4 100644
--- a/simple_form.gemspec
+++ b/simple_form.gemspec
@@ -19,6 +19,6 @@ Gem::Specification.new do |s|
 
   s.rubyforge_project = "simple_form"
 
-  s.add_dependency('activemodel', '~> 3.0')
-  s.add_dependency('actionpack', '~> 3.0')
+  s.add_dependency('activemodel', '>= 4.0.0.beta', '< 4.1')
+  s.add_dependency('actionpack', '>= 4.0.0.beta', '< 4.1')
 end