diff --git a/src/dynamic_graph/tools.py b/src/dynamic_graph/tools.py
index 75173fdfdbfae7f32e2d0151445ce88bb8325ce0..dd145a086885ac6270afc2bc2e870c6780970300 100644
--- a/src/dynamic_graph/tools.py
+++ b/src/dynamic_graph/tools.py
@@ -9,7 +9,7 @@ def addTrace(robot, trace, entityName, signalName, autoRecompute=True):
     Add a signal to a tracer and recompute it automatically if necessary.
     """
     signal = '{0}.{1}'.format(entityName, signalName)
-    filename = '{0}-{1}'.format(entityName, signalName)
+    filename = '{0}-{1}'.format(entityName, signalName).replace('/', '_')
     trace.add(signal, filename)
     if autoRecompute:
         robot.device.after.addSignal(signal)