diff --git a/trackers/roman_pot_simu.sh b/trackers/roman_pot_simu.sh
index 91ea178467e326adb416010e459b42e7e6c1ed51..c10ac633f8e131ca1ba7b12367996ac803715ad5 100755
--- a/trackers/roman_pot_simu.sh
+++ b/trackers/roman_pot_simu.sh
@@ -1,5 +1,7 @@
 #!/bin/bash
 
+source /usr/local/bin/thisdd4hep.sh
+
 ddsim --runType batch -N 300 \
 	--inputFiles ../data/forward_ions.hepmc \
 	--compactFile ./roman_pot.xml \