diff --git a/src/python/oftest/base_tests.py b/src/python/oftest/base_tests.py
index 734e213..7f29db5 100644
--- a/src/python/oftest/base_tests.py
+++ b/src/python/oftest/base_tests.py
@@ -76,6 +76,7 @@
         #@todo Review if join should be done on clean_shutdown
         if self.clean_shutdown:
             self.controller.join()
+        del self.controller
 
     def runTest(self):
         # Just a simple sanity check as illustration
@@ -112,6 +113,7 @@
         SimpleProtocol.tearDown(self)
         if hasattr(self, 'dataplane'):
             self.dataplane.kill(join_threads=self.clean_shutdown)
+            del self.dataplane
         logging.info("Teardown done")
 
     def runTest(self):
@@ -135,6 +137,7 @@
     def tearDown(self):
         logging.info("Teardown for simple dataplane test")
         self.dataplane.kill(join_threads=self.clean_shutdown)
+        del self.dataplane
         logging.info("Teardown done")
 
     def runTest(self):
diff --git a/src/python/oftest/dataplane.py b/src/python/oftest/dataplane.py
index ee3d7b1..a410aaf 100644
--- a/src/python/oftest/dataplane.py
+++ b/src/python/oftest/dataplane.py
@@ -508,6 +508,8 @@
                 self.logger.debug("Joining " + str(port_number))
                 self.port_list[port_number].join()
 
+        self.port_list = None
+
         self.logger.info("DataPlane shutdown")
 
     def show(self, prefix=''):