diff --git a/tests/port_stats.py b/tests/port_stats.py
index 7fac164..5f3a3f3 100644
--- a/tests/port_stats.py
+++ b/tests/port_stats.py
@@ -301,6 +301,9 @@
         return flow_mod_msg
 
     def runTest(self):
+        delete_all_flows(self.controller)
+        do_barrier(self.controller)
+
         # TODO: set from command-line parameter
         test_timeout = 60