diff --git a/app/views/site/prompt.html.haml b/app/views/site/prompt.html.haml
--- a/app/views/site/prompt.html.haml
+++ b/app/views/site/prompt.html.haml
@@ -17,6 +17,4 @@
   Please make sure that the contestants are ready.
   After the contest is started, it <b>cannot</b> be paused or stopped.
   %br/
-  = submit_tag 'Start the Contest.'
-
-    
+  = submit_tag 'Start the Contest.', :onclick => "return confirm('Are you sure?');"