diff --git a/calorimeters/Crystal_example.xml b/calorimeters/Crystal_example.xml
index 711e7d61b83a93f8605e421261829deb51fa7cfe..1a40a394dba36e3cdfd97f191a918fea99792aa7 100644
--- a/calorimeters/Crystal_example.xml
+++ b/calorimeters/Crystal_example.xml
@@ -24,6 +24,9 @@
     <constant name="world_y" value="world_side"/>
     <constant name="world_z" value="world_side"/>
 
+    <constant name="tracker_region_zmax" value="6 * m"/>
+    <constant name="tracker_region_rmax" value="6 * m"/>
+
     <constant name="CrystalEndcap_ID"    value="1"/>
     <constant name="CrystalEndcap_rmin"  value="120.0*mm"/> <!-- 12cm -->
     <constant name="CrystalEndcap_rmax"  value="600.0*mm"/> <!-- 60cm -->