diff --git a/lax/lichens/sciencerun0.py b/lax/lichens/sciencerun0.py
index c321798..b79a6d5 100644
--- a/lax/lichens/sciencerun0.py
+++ b/lax/lichens/sciencerun0.py
@@ -798,7 +798,7 @@ class MuonVeto(ManyLichen):
 
     Contact: Andrea Molinario <andrea.molinario@lngs.infn.it>
     """
-    version = 2
+    version = 3
 
     class MuonVetoCoincidence(StringLichen):
         """Checks the distance in time (ns) between a reference position inside the waveform
@@ -807,13 +807,13 @@ class MuonVetoCoincidence(StringLichen):
         with respect to the reference position.
         """
 
-        string = ("nearest_muon_veto_trigger < -2e6 | nearest_muon_veto_trigger > 3e6")
+        string = "nearest_muon_veto_trigger < -2e6 | nearest_muon_veto_trigger > 3e6"
 
     class MuonVetoOn(StringLichen):
         """Remove events when MV was not working (abs(nearest_muon_veto_trigger)>20 s).
         """
 
-        string = ("nearest_muon_veto_trigger > -2e10 & nearest_muon_veto_trigger < 2e10)")
+        string = "nearest_muon_veto_trigger > -2e10 & nearest_muon_veto_trigger < 2e10"
 
 
 class KryptonMisIdS1(StringLichen):