diff --git a/CHANGELOG.md b/CHANGELOG.md
index a5bce7e..e20bd56 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 - Use ERB templates instead of slim.
 - Don't check if `Sidekiq::Web.tabs` is an Array in Sidetiq::Web.
 - Fix Ruby parser warnings in web.rb.
+- Move development dependencies from Gemfile to gemspec.
 
 0.3.6
 -----
diff --git a/Gemfile b/Gemfile
index 611a2d8..9e9ddcc 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,16 +1,4 @@
 source 'https://rubygems.org'
 
-group :development do
-  gem 'rake'
-  gem 'sinatra', require: false
-  gem 'slim', require: false
-end
-
-group :test do
-  gem 'simplecov'
-  gem 'mocha'
-  gem 'rack-test'
-end
-
 gemspec
 
diff --git a/sidetiq.gemspec b/sidetiq.gemspec
index e718104..da00254 100644
--- a/sidetiq.gemspec
+++ b/sidetiq.gemspec
@@ -21,4 +21,10 @@ Gem::Specification.new do |gem|
 
   gem.add_dependency 'sidekiq',  '~> 2.14.0'
   gem.add_dependency 'ice_cube', '~> 0.11.0'
+
+  gem.add_development_dependency 'rake'
+  gem.add_development_dependency 'sinatra'
+  gem.add_development_dependency 'simplecov'
+  gem.add_development_dependency 'mocha'
+  gem.add_development_dependency 'rack-test'
 end