diff --git a/Detector/DetCRD/compact/CRD_common_v01/SET_SimplePlanar_v01_01.xml b/Detector/DetCRD/compact/CRD_common_v01/SET_SimplePlanar_v01_01.xml
index 5e39151764a31333ceb947a390e291c08082e015..d7f1dc5d0974b7159c8e2b955ae2c39e99d34d32 100644
--- a/Detector/DetCRD/compact/CRD_common_v01/SET_SimplePlanar_v01_01.xml
+++ b/Detector/DetCRD/compact/CRD_common_v01/SET_SimplePlanar_v01_01.xml
@@ -2,7 +2,7 @@
   <define>
     <constant name="SET_inner_radius" value="OuterTracker_outer_radius + env_safety"/>
     <constant name="SET_outer_radius" value="Ecal_barrel_inner_radius - env_safety "/>
-    <constant name="SET_half_length"  value="OuterTracker_half_length"/>
+    <constant name="SET_half_length"  value="MainTracker_half_length"/>
   </define>
 
   <detectors>
diff --git a/Detector/DetCRD/compact/CRD_common_v01/SET_SimplePlanar_v01_02.xml b/Detector/DetCRD/compact/CRD_common_v01/SET_SimplePlanar_v01_02.xml
index 2d90b1c81d0a5e41831bbd2f2dc19b3739e604d3..0d3621a4841f9b142655b2d51447bc8da6d4f76e 100644
--- a/Detector/DetCRD/compact/CRD_common_v01/SET_SimplePlanar_v01_02.xml
+++ b/Detector/DetCRD/compact/CRD_common_v01/SET_SimplePlanar_v01_02.xml
@@ -2,7 +2,7 @@
   <define>
     <constant name="SET_inner_radius" value="OuterTracker_outer_radius + env_safety"/>
     <constant name="SET_outer_radius" value="Ecal_barrel_inner_radius - env_safety "/>
-    <constant name="SET_half_length"  value="OuterTracker_half_length"/>
+    <constant name="SET_half_length"  value="MainTracker_half_length"/>
     <constant name="SET_inner_distance_from_tpc" value="InnerTracker_outer_radius-OuterTracker_outer_radius+3*mm"/>
   </define>