diff --git a/lib/zss/socket.rb b/lib/zss/socket.rb
index <HASH>..<HASH> 100644
--- a/lib/zss/socket.rb
+++ b/lib/zss/socket.rb
@@ -80,7 +80,7 @@ module ZSS
       first   = frames.shift
       last   = frames.pop
       frames.each { |f| check! socket.send_string f.to_s, ZMQ::SNDMORE }
-      check! socket.send_string last
+      check! socket.send_string last.to_s
     end
 
     def receive_message socket
last frame should be send as string also

This didn't blow because at the moment the last frame is a string