diff --git a/app.rb b/app.rb
index a7a9ba5..736d0dc 100644
--- a/app.rb
+++ b/app.rb
@@ -19,8 +19,10 @@ class App < Roda
 
     r.post "create" do
       url = r.params['url']
-      code = SecureRandom.urlsafe_base64 4
-      links.insert(url: url, code: code) 
+      if nil == links.filter(:url => url).first
+        code = SecureRandom.urlsafe_base64 5
+        links.insert(url: url, code: code) 
+      end
       @new_link = 'http://' + request.env['HTTP_HOST'] + '/' + links.filter(:url => url).first[:code]
       view :create   
     end