diff --git a/Gemfile.lock b/Gemfile.lock
index 7bcf4149..76febd83 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -2,34 +2,34 @@ PATH
   remote: .
   specs:
     simple_form (3.4.0)
-      actionpack (> 4, < 5.1)
-      activemodel (> 4, < 5.1)
+      actionpack (> 4, < 5.2)
+      activemodel (> 4, < 5.2)
 
 GEM
   remote: https://rubygems.org/
   specs:
-    actionpack (5.0.1)
-      actionview (= 5.0.1)
-      activesupport (= 5.0.1)
+    actionpack (5.1.0)
+      actionview (= 5.1.0)
+      activesupport (= 5.1.0)
       rack (~> 2.0)
       rack-test (~> 0.6.3)
       rails-dom-testing (~> 2.0)
       rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    actionview (5.0.1)
-      activesupport (= 5.0.1)
+    actionview (5.1.0)
+      activesupport (= 5.1.0)
       builder (~> 3.1)
-      erubis (~> 2.7.0)
+      erubi (~> 1.4)
       rails-dom-testing (~> 2.0)
-      rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    activemodel (5.0.1)
-      activesupport (= 5.0.1)
-    activesupport (5.0.1)
+      rails-html-sanitizer (~> 1.0, >= 1.0.3)
+    activemodel (5.1.0)
+      activesupport (= 5.1.0)
+    activesupport (5.1.0)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (~> 0.7)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
-    builder (3.2.2)
-    concurrent-ruby (1.0.4)
+    builder (3.2.3)
+    concurrent-ruby (1.0.5)
     countries (1.2.5)
       currencies (~> 0.4.2)
       i18n_data (~> 0.7.0)
@@ -37,16 +37,16 @@ GEM
       countries (~> 1.2.0)
       sort_alphabetical (~> 1.0)
     currencies (0.4.2)
-    erubis (2.7.0)
+    erubi (1.6.0)
     ffi2-generators (0.1.1)
-    i18n (0.7.0)
+    i18n (0.8.1)
     i18n_data (0.7.0)
     loofah (2.0.3)
       nokogiri (>= 1.5.9)
     method_source (0.8.2)
     mini_portile2 (2.1.0)
     minitest (5.10.1)
-    nokogiri (1.7.0.1)
+    nokogiri (1.7.1)
       mini_portile2 (~> 2.1.0)
     rack (2.0.1)
     rack-test (0.6.3)
@@ -56,9 +56,9 @@ GEM
       nokogiri (~> 1.6)
     rails-html-sanitizer (1.0.3)
       loofah (~> 2.0)
-    railties (5.0.1)
-      actionpack (= 5.0.1)
-      activesupport (= 5.0.1)
+    railties (5.1.0)
+      actionpack (= 5.1.0)
+      activesupport (= 5.1.0)
       method_source
       rake (>= 0.8.7)
       thor (>= 0.18.1, < 2.0)
@@ -248,7 +248,7 @@ GEM
     rubysl-set (2.0.1)
     rubysl-shellwords (2.0.0)
     rubysl-singleton (2.0.0)
-    rubysl-socket (2.2)
+    rubysl-socket (2.2.1)
       rubysl-fcntl (~> 2.0)
     rubysl-stringio (2.1.0)
     rubysl-strscan (2.0.0)
@@ -275,8 +275,8 @@ GEM
     sort_alphabetical (1.1.0)
       unicode_utils (>= 1.2.2)
     thor (0.19.4)
-    thread_safe (0.3.5)
-    tzinfo (1.2.2)
+    thread_safe (0.3.6)
+    tzinfo (1.2.3)
       thread_safe (~> 0.1)
     unicode_utils (1.4.0)
 
@@ -292,4 +292,4 @@ DEPENDENCIES
   simple_form!
 
 BUNDLED WITH
-   1.14.0.pre.1
+   1.14.6
diff --git a/simple_form.gemspec b/simple_form.gemspec
index 30d2bc57..f77089b8 100644
--- a/simple_form.gemspec
+++ b/simple_form.gemspec
@@ -20,6 +20,6 @@ Gem::Specification.new do |s|
 
   s.rubyforge_project = "simple_form"
 
-  s.add_dependency('activemodel', '> 4', '< 5.1')
-  s.add_dependency('actionpack', '> 4', '< 5.1')
+  s.add_dependency('activemodel', '> 4', '< 5.2')
+  s.add_dependency('actionpack', '> 4', '< 5.2')
 end
diff --git a/test/support/mock_controller.rb b/test/support/mock_controller.rb
index c0cd80a8..f7b8f15a 100644
--- a/test/support/mock_controller.rb
+++ b/test/support/mock_controller.rb
@@ -9,7 +9,7 @@ class MockController
     defined?(@action_name) ? @action_name : "edit"
   end
 
-  def url_for(*args)
+  def url_for(*)
     "http://example.com"
   end
 
@@ -17,6 +17,8 @@ class MockController
     {}
   end
 
+  def polymorphic_mappings(*); {}; end
+
   def hash_for_user_path(*); end
   def hash_for_validating_user_path(*); end
   def hash_for_other_validating_user_path(*); end
diff --git a/test/support/models.rb b/test/support/models.rb
index e8dfcb7b..79f6277b 100644
--- a/test/support/models.rb
+++ b/test/support/models.rb
@@ -128,6 +128,7 @@ class User
 
   begin
     require 'active_model/type'
+    require 'active_record/type'
     def type_for_attribute(attribute)
       column_type, limit = case attribute
         when 'name', 'status', 'password' then [:string, 100]
@@ -148,7 +149,11 @@ class User
         when 'uuid'          then :string
       end
 
-      ActiveModel::Type.lookup(column_type, limit: limit)
+      begin
+        ActiveModel::Type.lookup(column_type, limit: limit)
+      rescue ArgumentError
+        ActiveRecord::Type.lookup(column_type, limit: limit)
+      end
     end
   rescue LoadError
   end