diff --git a/lib/cassandra.rb b/lib/cassandra.rb
index 83c8f8cdd..316d53695 100644
--- a/lib/cassandra.rb
+++ b/lib/cassandra.rb
@@ -29,6 +29,7 @@
 require 'resolv'
 require 'openssl'
 require 'securerandom'
+require 'sorted_set'
 require 'time'
 require 'date'