diff --git a/compact/cb_DIRC.xml b/compact/cb_DIRC.xml
index 91c95359c7de52765f7c573eef532b20331c4fca..ad75cd6dff7ef5891dfbc5342c62e3cfd9726c82 100644
--- a/compact/cb_DIRC.xml
+++ b/compact/cb_DIRC.xml
@@ -7,7 +7,7 @@
   </comment>
 
   <define>
-    <constant name="cb_DIRC_length"            value="EcalBarrelLength"/>
+    <constant name="cb_DIRC_length"            value="DIRCLength"/>
     <constant name="cb_DIRC_rmin"              value="82.00*cm"/>
     <constant name="cb_DIRC_rmax"              value="88.00*cm"/>
   </define>
@@ -24,7 +24,7 @@
   <detectors>
     <detector id="BarrelDIRC_ID" name="cb_DIRC" type="cb_DIRC" readout="DIRCHits" vis="AnlTeal">
       <dimensions rmin="cb_DIRC_rmin" rmax="cb_DIRC_rmax" length="cb_DIRC_length"/>
-      <position x="0" y="0" z="EcalBarrel_offset"/>
+      <position x="0" y="0" z="DIRC_offset"/>
     </detector>
   </detectors>
 
diff --git a/compact/definitions.xml b/compact/definitions.xml
index b9d31dfbbf7e3d3087f49a4d0cda26b14ff9aa5f..a2c03999bfc848cf46581140d16751b47205d5eb 100644
--- a/compact/definitions.xml
+++ b/compact/definitions.xml
@@ -609,6 +609,14 @@
     <constant name="HcalEndcapP_thickness" value="HcalEndcapPLayer_NRepeat * HcalSingleLayerThickness"/>
     <constant name="HcalEndcapN_thickness" value="HcalEndcapNLayer_NRepeat * HcalSingleLayerThickness"/>
 
+    <comment>
+      ----------------------
+      DIRC parameters
+      ----------------------
+    </comment>
+    <constant name="DIRCLength"           value="CentralTracking_length + BackwardPIDLength"/>
+    <constant name="DIRCOffset"           value="(CentralTracking_length - DIRCLength)/2.0"/>
+
     <comment>
       ----------------------
       Zero Degree Parameters