diff --git a/lib/sinatra/flash.rb b/lib/sinatra/flash.rb
index 07b07ff..371d4ca 100644
--- a/lib/sinatra/flash.rb
+++ b/lib/sinatra/flash.rb
@@ -12,10 +12,10 @@ def self.registered(app)
 
       # This callback rotates any flash structure we referenced, placing the 'next' hash into the session
       # for the next request.
-      app.after {@flash.each{|key, flash| session[key] = @flash[key].next} if @flash}
+      app.after {@flash.each{|key, flash| session[key] = @flash[key].next} if defined? @flash}
     end
 
   end
   
   register Flash
-end
\ No newline at end of file
+end