diff --git a/lib/sidekiq/redis_connection.rb b/lib/sidekiq/redis_connection.rb
index 53f348fe..ecd1741e 100644
--- a/lib/sidekiq/redis_connection.rb
+++ b/lib/sidekiq/redis_connection.rb
@@ -27,7 +27,7 @@ module Sidekiq
     end
 
     def self.url
-      ENV['REDISTOGO_URL'] || @url
+      ENV['REDISTOGO_URL'] || (@url = nil)
     end
 
     def self.namespace=(namespace)