diff --git a/lib/travis/web/app/mobile_redirect.rb b/lib/travis/web/app/mobile_redirect.rb
index 5593b9e5..f2ecaaf7 100644
--- a/lib/travis/web/app/mobile_redirect.rb
+++ b/lib/travis/web/app/mobile_redirect.rb
@@ -2,7 +2,7 @@ class Travis::Web::App::MobileRedirect < Struct.new(:app)
   def call(env)
     request = Rack::Request.new env
 
-    if request.params['mobile'] || env['HTTP_AGENT'] =~ /Mobile|webOS/
+    if request.params['mobile'] || request.user_agent.to_s =~ /Mobile|webOS/
       location = 'https://secure.travis-ci.org' + request.fullpath
       [301, { 'Content-Type' => 'text/plain', 'Location' => location }, []]
     else
diff --git a/spec/mobile_redirect_spec.rb b/spec/mobile_redirect_spec.rb
index 03871d53..490cfae4 100644
--- a/spec/mobile_redirect_spec.rb
+++ b/spec/mobile_redirect_spec.rb
@@ -6,7 +6,7 @@ describe Travis::Web::App::MobileRedirect do
     let(:agent) { 'blah blah Mobile blablah' }
 
     it 'redirects to secure.travis-ci.org' do
-      get('/foo/bar?baz', {}, 'HTTP_AGENT' => agent).should be_redirect
+      get('/foo/bar?baz', {}, 'HTTP_USER_AGENT' => agent).should be_redirect
       last_response.headers['Location'].should == 'https://secure.travis-ci.org/foo/bar?baz'
     end
   end