diff --git a/lib/serve/application.rb b/lib/serve/application.rb
index ad4c1f4..5e42317 100644
--- a/lib/serve/application.rb
+++ b/lib/serve/application.rb
@@ -160,7 +160,7 @@ def extract_environment(args)
       end
       
       def extract_port(args)
-        (args.delete(args.find {|a| /^\d\d\d*$/.match(a) }) || ((rails_app? or rack_app?) ? 3000 : 4000)).to_i
+        (args.delete(args.find {|a| /^\d\d\d*$/.match(a) }) || ENV['PORT'] || 4000).to_i
       end
       
       def extract_address(args)
@@ -234,15 +234,15 @@ def extract_export(args)
           }
         end
       end
-      
+
       def rails_script_server
         @rails_server_script ||= options[:root] + '/script/server'
       end
-      
+
       def rails_app?
         File.file?(rails_script_server) and File.executable?(rails_script_server)
       end
-      
+
       def run_rails_app
         system "#{rails_script_server} -p #{options[:port]} -b #{options[:address]} -e #{options[:environment]}"
       end
diff --git a/lib/serve/bootstrap/config.ru b/lib/serve/bootstrap/config.ru
index 82dd519..0310065 100644
--- a/lib/serve/bootstrap/config.ru
+++ b/lib/serve/bootstrap/config.ru
@@ -1,5 +1,3 @@
-#\ -p 4000
-
 require 'rubygems'
 require 'bundler'
 begin
@@ -44,4 +42,4 @@ else
     Serve::RackAdapter.new(root + '/views'),
     Rack::Directory.new(root + '/public')
   ])
-end
\ No newline at end of file
+end
diff --git a/spec/application_spec.rb b/spec/application_spec.rb
index b176da1..b48e246 100644
--- a/spec/application_spec.rb
+++ b/spec/application_spec.rb
@@ -39,6 +39,11 @@
       parse('http://1.1.1.1:2000').should == @options.update(:address => "1.1.1.1", :port=>2000)
     end
     
+    it "with port set in ENV" do
+      ENV["PORT"] = "4321"
+      parse[:port].should == 4321
+    end
+    
     it "help" do
       parse('')[:help].should be_false
       parse('-h')[:help].should be_true
@@ -150,4 +155,4 @@ def parse(*args)
     
   end
   
-end
\ No newline at end of file
+end
diff --git a/website/config.ru b/website/config.ru
index 7f8dfad..ce48a2a 100644
--- a/website/config.ru
+++ b/website/config.ru
@@ -1,5 +1,3 @@
-#\ -p 4000
-
 require 'rubygems'
 require 'bundler'
 begin