diff --git a/src/DetectorConstruction.cc b/src/DetectorConstruction.cc
index 620aa31..1a079fb 100644
--- a/src/DetectorConstruction.cc
+++ b/src/DetectorConstruction.cc
@@ -280,7 +280,9 @@ G4VPhysicalVolume* DetectorConstruction::DefineVolumes()
       if(layer.isActive){
          for(int i = 0; i < layer.nx * layer.ny; i++){
              Sensor sensor;
-             sensor.position = parametrisation->ComputePosition(i);
+             // add z position of layer to in-layer position of sensor
+             sensor.position = parametrisation->ComputePosition(i) + 
+             G4ThreeVector(0,0,position);
              //G4ThreeVector(layer.sens_xwidth * (i % layer.nx) - layer.sens_xwidth * ((float)layer.nx-1) / 2.*cm, // FIX!!!!
              //layer.sens_ywidth * (i / layer.nx) - layer.sens_ywidth * ((float)layer.ny-1) / 2.*cm, position);
              sensor.size = G4ThreeVector(layer.sens_xwidth *cm, layer.sens_ywidth*cm, layer.thickness*cm);