diff --git a/run/LEM_15kV_2013_SR-10deg_L1-9.0_L2-10.5_L3-11.5_RA-11.9.mac b/run/LEM_15kV_2013_SR-10deg_L1-9.0_L2-10.5_L3-11.5_RA-11.9.mac
index 200376d..0fe6c17 100644
--- a/run/LEM_15kV_2013_SR-10deg_L1-9.0_L2-10.5_L3-11.5_RA-11.9.mac
+++ b/run/LEM_15kV_2013_SR-10deg_L1-9.0_L2-10.5_L3-11.5_RA-11.9.mac
@@ -688,6 +688,7 @@
 #/musr/command process addProcess         mu+   G4MuPairProduction       -1  4  4
 #/musr/command process addDiscreteProcess mu+   G4CoulombScattering
 #/musr/command process addProcess        mu+   G4StepLimiter             -1  -1  5
+/musr/command process addProcess          mu+   musrMuFormation     -1 -1 2
 
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