diff --git a/tools/test/topos/onos.py b/tools/test/topos/onos.py
index 00670b5..18f2212 100755
--- a/tools/test/topos/onos.py
+++ b/tools/test/topos/onos.py
@@ -87,7 +87,7 @@
         # TODO 4. Update config/cluster.json : with all nodes
 
         # start onos
-        self.userCmd( self.instanceDir + 'bin/start' )
+        self.userCmd( '%sbin/instance start -d %s' % ( self.karafDir, self.name ) )
         #TODO we should wait for startup...
 
     def stop( self ):