diff --git a/tools/test/topos/opticalUtils.py b/tools/test/topos/opticalUtils.py
index b5147fe..68e2b38 100644
--- a/tools/test/topos/opticalUtils.py
+++ b/tools/test/topos/opticalUtils.py
@@ -430,6 +430,7 @@
         i = 0
         for ctrl in controllers:
             self.addController( RemoteController( 'c%d' % i, ip=ctrl ) )
+            i += 1
 
 
 class OpticalTestTopo( Topo ):