diff --git a/LArCalorimeter/LArG4/LArG4HEC/src/HECGeometry.cc b/LArCalorimeter/LArG4/LArG4HEC/src/HECGeometry.cc
index b00268bfcf95efa559cfb6e7aefe9711bd4ee031..8c05dccac2bebac10397cfb335a2002e727b3ad6 100644
--- a/LArCalorimeter/LArG4/LArG4HEC/src/HECGeometry.cc
+++ b/LArCalorimeter/LArG4/LArG4HEC/src/HECGeometry.cc
@@ -285,7 +285,7 @@ namespace LArG4 {
 
             G4Tubs *tubs = dynamic_cast<G4Tubs *> (sliceSolid);
             if (tubs) {
-              double dz = tubs->GetDz()/Units::mm;
+              double dz = tubs->GetZHalfLength()/Units::mm;
               if (sliceZ > 0) {
                 if (fabs(sliceZ)>dz/2.0) {
                   (*subgap) = 0;