diff --git a/python/pygimli/physics/traveltime/refraction.py b/python/pygimli/physics/traveltime/refraction.py
index 13d3fc47a..7e42080ae 100644
--- a/python/pygimli/physics/traveltime/refraction.py
+++ b/python/pygimli/physics/traveltime/refraction.py
@@ -483,7 +483,7 @@ def simulate(mesh, slowness, scheme, verbose=False, **kwargs):
             if not ret.allNonZero('err'):
                 ret.set('t', t)
                 ret.set('err', pg.physics.Refraction.estimateError(
-                    ret, absoluteError=noiseAbs)
+                    ret, absoluteError=noiseAbs))
 
             if verbose:
                 print("Data error estimates (min:max) ",