diff --git a/examples/traffic-control/cobalt-vs-codel.cc b/examples/traffic-control/cobalt-vs-codel.cc
index 9f55cd61a..d5b72c4c1 100644
--- a/examples/traffic-control/cobalt-vs-codel.cc
+++ b/examples/traffic-control/cobalt-vs-codel.cc
@@ -28,7 +28,6 @@
 #include "ns3/ipv6-static-routing-helper.h"
 #include "ns3/ipv6-routing-table-entry.h"
 #include "ns3/internet-module.h"
-#include "ns3/flow-monitor-module.h"
 #include "ns3/tcp-header.h"
 #include "ns3/traffic-control-module.h"
 #include  <string>
@@ -230,16 +229,13 @@ void experiment (std::string queue_disc_type)
   Ptr<QueueDisc> queue = queueDiscs.Get (0);
   Simulator::ScheduleNow (&CheckQueueSize, queue,queue_disc_type);
 
-  int n;
   std::string dirToSave = "mkdir -p " + dir + queue_disc_type;
-  n = system (dirToSave.c_str ());
-  n = system ((dirToSave + "/cwndTraces/").c_str ());
-  n = system ((dirToSave + "/queueTraces/").c_str ());
-
-  if (n == -1)
+  if (system ((dirToSave + "/cwndTraces/").c_str ()) == -1
+      || system ((dirToSave + "/queueTraces/").c_str ()) == -1)
     {
       exit (1);
     }
+
   Simulator::Schedule (Seconds (0.1), &TraceCwnd,queue_disc_type);
 
   Simulator::Stop (Seconds (stopTime));