diff --git a/lib/travis/web/app.rb b/lib/travis/web/app.rb
index f4b0b220..f7a73f80 100644
--- a/lib/travis/web/app.rb
+++ b/lib/travis/web/app.rb
@@ -6,6 +6,7 @@ module Travis::Web
     autoload :Api,      'travis/web/app/api'
     autoload :Config,   'travis/web/app/config'
     autoload :Files,    'travis/web/app/files'
+    autoload :Helpers,  'travis/web/app/helpers'
     autoload :Filter,   'travis/web/app/filter'
     autoload :Terminal, 'travis/web/app/terminal'
     autoload :Version,  'travis/web/app/version'
@@ -26,15 +27,7 @@ module Travis::Web
         use Rack::Protection::PathTraversal
         use Rack::Deflater if config.deflate?
 
-        # TODO this doesn't work, how can i extract this to a separate file/class
-        # use Travis::Web::App::Api, config if config.run_api?
-        if config.run_api?
-          require 'travis/api/app'
-          map config.api_endpoint do
-            run Travis::Api::App.new
-          end
-        end
-
+        use Travis::Web::App::Api, config if config.run_api?
         use Travis::Web::App::Version, config
         use Travis::Web::App::Filter, config
         run Travis::Web::App::Files.new
diff --git a/lib/travis/web/app/api.rb b/lib/travis/web/app/api.rb
index eec7efb1..88199d57 100644
--- a/lib/travis/web/app/api.rb
+++ b/lib/travis/web/app/api.rb
@@ -2,6 +2,8 @@ require 'travis/api/app'
 
 class Travis::Web::App
   class Api
+    include Helpers
+
     attr_reader :app, :api, :config
 
     def initialize(app, config)
@@ -11,22 +13,17 @@ class Travis::Web::App
     end
 
     def call(env)
-      path = env['PATH_INFO']
-      if matches?(path)
-        api.call(env.merge('PATH_INFO' => api_path(path)))
+      if matches?(env['PATH_INFO'])
+        api.call(map_env(env, config.api_endpoint))
       else
         app.call(env)
       end
     end
 
-    def matches?(path)
-      # TODO there's a redirect through /auth/post_message which doesn't have the /api
-      # prefix. is that safe_redirect in travis-api? not sure how to solve this
-      path.starts_with?(config.api_endpoint) || path.starts_with?('/auth')
-    end
+    private
 
-    def api_path(path)
-      path.sub(/^#{config.api_endpoint}/, '')
-    end
+      def matches?(path)
+        path.starts_with?(config.api_endpoint)
+      end
   end
 end
diff --git a/lib/travis/web/app/filter/endpoint.rb b/lib/travis/web/app/filter/endpoint.rb
index ce3b540f..72e23bcc 100644
--- a/lib/travis/web/app/filter/endpoint.rb
+++ b/lib/travis/web/app/filter/endpoint.rb
@@ -9,7 +9,11 @@ class Travis::Web::App::Filter
     end
 
     def apply(string)
-      string.gsub(DEFAULT_ENDPOINT, config.api_endpoint)
+      apply? ? string.gsub(DEFAULT_ENDPOINT, config.api_endpoint) : string
+    end
+
+    def apply?
+      config.api_endpoint != DEFAULT_ENDPOINT
     end
   end
 end
diff --git a/lib/travis/web/app/filter/version.rb b/lib/travis/web/app/filter/version.rb
index a0146332..31111fa5 100644
--- a/lib/travis/web/app/filter/version.rb
+++ b/lib/travis/web/app/filter/version.rb
@@ -13,4 +13,3 @@ class Travis::Web::App::Filter
     end
   end
 end
-
diff --git a/lib/travis/web/app/helpers.rb b/lib/travis/web/app/helpers.rb
new file mode 100644
index 00000000..d148aacf
--- /dev/null
+++ b/lib/travis/web/app/helpers.rb
@@ -0,0 +1,11 @@
+class Travis::Web::App
+  module Helpers
+    # TODO what's a better name?
+    def map_env(env, segment)
+      segment = "/#{segment}" unless segment[0] == '/'
+      env['PATH_INFO'] = env['PATH_INFO'].gsub(%r(^#{segment}(?:/)), '')
+      env['SCRIPT_NAME'] = "#{env['SCRIPT_NAME']}#{segment}"
+      env
+    end
+  end
+end
diff --git a/lib/travis/web/app/version.rb b/lib/travis/web/app/version.rb
index fbedbd62..74205bc6 100644
--- a/lib/travis/web/app/version.rb
+++ b/lib/travis/web/app/version.rb
@@ -1,5 +1,7 @@
 class Travis::Web::App
   class Version
+    include Helpers
+
     attr_reader :app, :config
 
     def initialize(app, config)
@@ -12,9 +14,9 @@ class Travis::Web::App
       if pass?(path)
         app.call(env)
       elsif versioned?(path)
-        app.call(env.merge('PATH_INFO' => strip_version(path)))
+        app.call(map_env(env, config.version))
       else
-       [404, { 'Content-Type' => 'text/html', 'Content-Length' => '9' }, ['not found']]
+        not_found
       end
     end
 
@@ -28,8 +30,8 @@ class Travis::Web::App
         path.starts_with?("/#{config.version}/")
       end
 
-      def strip_version(path)
-        path.sub(%r(/#{config.version}/), '')
+      def not_found
+        [404, { 'Content-Type' => 'text/html', 'Content-Length' => '9', 'X-Cascade' => 'pass' }, ['not found']]
       end
   end
 end