diff --git a/options/reconstruction.py b/options/reconstruction.py
index cbe6c2f40c05bef9813d283ed09d2b1bb9998b5a..b5ef338fefdcd144aee53a24921b0f54caf1a9d2 100644
--- a/options/reconstruction.py
+++ b/options/reconstruction.py
@@ -666,7 +666,7 @@ trk_find_alg = CKFTracking("trk_find_alg",
         inputMeasurements = sourcelinker.outputMeasurements,
         inputInitialTrackParameters = truth_trk_init.outputInitialTrackParameters,
         outputTrajectories = "trajectories",
-	chi2CutOff = 50	
+	chi2CutOff = [50.]	
 )
 algorithms.append(trk_find_alg)