diff --git a/Gemfile.lock b/Gemfile.lock
index 039bfde..28c2b8f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -7,77 +7,133 @@ PATH
 GEM
   remote: http://rubygems.org/
   specs:
-    abstract (1.0.0)
-    actionmailer (3.0.11)
-      actionpack (= 3.0.11)
-      mail (~> 2.2.19)
-    actionpack (3.0.11)
-      activemodel (= 3.0.11)
-      activesupport (= 3.0.11)
-      builder (~> 2.1.2)
-      erubis (~> 2.6.6)
-      i18n (~> 0.5.0)
-      rack (~> 1.2.1)
-      rack-mount (~> 0.6.14)
-      rack-test (~> 0.5.7)
-      tzinfo (~> 0.3.23)
-    activemodel (3.0.11)
-      activesupport (= 3.0.11)
-      builder (~> 2.1.2)
-      i18n (~> 0.5.0)
-    activerecord (3.0.11)
-      activemodel (= 3.0.11)
-      activesupport (= 3.0.11)
-      arel (~> 2.0.10)
-      tzinfo (~> 0.3.23)
-    activeresource (3.0.11)
-      activemodel (= 3.0.11)
-      activesupport (= 3.0.11)
-    activesupport (3.0.11)
-    arel (2.0.10)
-    builder (2.1.2)
+    actioncable (6.0.0)
+      actionpack (= 6.0.0)
+      nio4r (~> 2.0)
+      websocket-driver (>= 0.6.1)
+    actionmailbox (6.0.0)
+      actionpack (= 6.0.0)
+      activejob (= 6.0.0)
+      activerecord (= 6.0.0)
+      activestorage (= 6.0.0)
+      activesupport (= 6.0.0)
+      mail (>= 2.7.1)
+    actionmailer (6.0.0)
+      actionpack (= 6.0.0)
+      actionview (= 6.0.0)
+      activejob (= 6.0.0)
+      mail (~> 2.5, >= 2.5.4)
+      rails-dom-testing (~> 2.0)
+    actionpack (6.0.0)
+      actionview (= 6.0.0)
+      activesupport (= 6.0.0)
+      rack (~> 2.0)
+      rack-test (>= 0.6.3)
+      rails-dom-testing (~> 2.0)
+      rails-html-sanitizer (~> 1.0, >= 1.2.0)
+    actiontext (6.0.0)
+      actionpack (= 6.0.0)
+      activerecord (= 6.0.0)
+      activestorage (= 6.0.0)
+      activesupport (= 6.0.0)
+      nokogiri (>= 1.8.5)
+    actionview (6.0.0)
+      activesupport (= 6.0.0)
+      builder (~> 3.1)
+      erubi (~> 1.4)
+      rails-dom-testing (~> 2.0)
+      rails-html-sanitizer (~> 1.1, >= 1.2.0)
+    activejob (6.0.0)
+      activesupport (= 6.0.0)
+      globalid (>= 0.3.6)
+    activemodel (6.0.0)
+      activesupport (= 6.0.0)
+    activerecord (6.0.0)
+      activemodel (= 6.0.0)
+      activesupport (= 6.0.0)
+    activestorage (6.0.0)
+      actionpack (= 6.0.0)
+      activejob (= 6.0.0)
+      activerecord (= 6.0.0)
+      marcel (~> 0.3.1)
+    activesupport (6.0.0)
+      concurrent-ruby (~> 1.0, >= 1.0.2)
+      i18n (>= 0.7, < 2)
+      minitest (~> 5.1)
+      tzinfo (~> 1.1)
+      zeitwerk (~> 2.1, >= 2.1.8)
+    builder (3.2.3)
+    concurrent-ruby (1.1.5)
     contest (0.1.2)
-    erubis (2.6.6)
-      abstract (>= 1.0.0)
-    i18n (0.5.0)
-    json (1.6.5)
-    mail (2.2.19)
-      activesupport (>= 2.3.6)
-      i18n (>= 0.4.0)
-      mime-types (~> 1.16)
-      treetop (~> 1.4.8)
-    mime-types (1.17.2)
+    crass (1.0.5)
+    erubi (1.9.0)
+    globalid (0.4.2)
+      activesupport (>= 4.2.0)
+    i18n (1.7.0)
+      concurrent-ruby (~> 1.0)
+    loofah (2.3.0)
+      crass (~> 1.0.2)
+      nokogiri (>= 1.5.9)
+    mail (2.7.1)
+      mini_mime (>= 0.1.1)
+    marcel (0.3.3)
+      mimemagic (~> 0.3.2)
+    method_source (0.9.2)
+    mimemagic (0.3.3)
+    mini_mime (1.0.2)
+    mini_portile2 (2.4.0)
+    minitest (5.12.2)
     mocha (0.9.12)
-    polyglot (0.3.3)
-    rack (1.2.5)
-    rack-mount (0.6.14)
-      rack (>= 1.0.0)
-    rack-test (0.5.7)
-      rack (>= 1.0)
-    rails (3.0.11)
-      actionmailer (= 3.0.11)
-      actionpack (= 3.0.11)
-      activerecord (= 3.0.11)
-      activeresource (= 3.0.11)
-      activesupport (= 3.0.11)
-      bundler (~> 1.0)
-      railties (= 3.0.11)
-    railties (3.0.11)
-      actionpack (= 3.0.11)
-      activesupport (= 3.0.11)
+    nio4r (2.5.2)
+    nokogiri (1.10.4)
+      mini_portile2 (~> 2.4.0)
+    rack (2.0.7)
+    rack-test (1.1.0)
+      rack (>= 1.0, < 3)
+    rails (6.0.0)
+      actioncable (= 6.0.0)
+      actionmailbox (= 6.0.0)
+      actionmailer (= 6.0.0)
+      actionpack (= 6.0.0)
+      actiontext (= 6.0.0)
+      actionview (= 6.0.0)
+      activejob (= 6.0.0)
+      activemodel (= 6.0.0)
+      activerecord (= 6.0.0)
+      activestorage (= 6.0.0)
+      activesupport (= 6.0.0)
+      bundler (>= 1.3.0)
+      railties (= 6.0.0)
+      sprockets-rails (>= 2.0.0)
+    rails-dom-testing (2.0.3)
+      activesupport (>= 4.2.0)
+      nokogiri (>= 1.6)
+    rails-html-sanitizer (1.3.0)
+      loofah (~> 2.3)
+    railties (6.0.0)
+      actionpack (= 6.0.0)
+      activesupport (= 6.0.0)
+      method_source
       rake (>= 0.8.7)
-      rdoc (~> 3.4)
-      thor (~> 0.14.4)
-    rake (0.9.2.2)
-    rdoc (3.12)
-      json (~> 1.4)
+      thor (>= 0.20.3, < 2.0)
+    rake (13.0.0)
+    sprockets (4.0.0)
+      concurrent-ruby (~> 1.0)
+      rack (> 1, < 3)
+    sprockets-rails (3.2.1)
+      actionpack (>= 4.0)
+      activesupport (>= 4.0)
+      sprockets (>= 3.0.0)
     sqlite3 (1.3.5)
     test-unit (2.2.0)
-    thor (0.14.6)
-    treetop (1.4.10)
-      polyglot
-      polyglot (>= 0.3.1)
-    tzinfo (0.3.31)
+    thor (0.20.3)
+    thread_safe (0.3.6)
+    tzinfo (1.2.5)
+      thread_safe (~> 0.1)
+    websocket-driver (0.7.1)
+      websocket-extensions (>= 0.1.0)
+    websocket-extensions (0.1.4)
+    zeitwerk (2.2.0)
 
 PLATFORMS
   ruby
@@ -85,7 +141,7 @@ PLATFORMS
 DEPENDENCIES
   contest
   mocha
-  rails (= 3.0.11)
+  rails (>= 3.0.0)
   sqlite3
   test-unit
   themes_for_rails!
diff --git a/themes_for_rails.gemspec b/themes_for_rails.gemspec
index d1d21c0..c59eeba 100644
--- a/themes_for_rails.gemspec
+++ b/themes_for_rails.gemspec
@@ -16,10 +16,10 @@ Gem::Specification.new do |gem|
   gem.require_paths = ["lib"]
   gem.version       = ThemesForRails::VERSION
 
-  gem.add_dependency('rails', [">= 3.0.0"])
+  gem.add_dependency('rails', ">= 3.0.0")
   gem.add_development_dependency "sqlite3"
   gem.add_development_dependency "test-unit"
   gem.add_development_dependency "contest"
   gem.add_development_dependency "mocha"
-  gem.add_development_dependency('rails', ["= 3.0.11"])
+  gem.add_development_dependency('rails', ">= 3.0.0")
 end