diff --git a/lib/net/pop.rb b/lib/net/pop.rb
index af4948c..3e297b1 100644
--- a/lib/net/pop.rb
+++ b/lib/net/pop.rb
@@ -484,6 +484,7 @@ def inspect
     #
     def set_debug_output(arg)
       @debug_output = arg
+      @socket.debug_output = arg if @socket
     end
 
     # The address to connect to.