diff --git a/topside/silicon_tracker.xml b/topside/silicon_tracker.xml
index e19dedd77bf1fcb89df8faf23091f25f1b9af64d..7cfcb590b4211c3331ba0450327bd41529e2be71 100644
--- a/topside/silicon_tracker.xml
+++ b/topside/silicon_tracker.xml
@@ -1004,8 +1004,8 @@
 
   <readouts>
     <readout name="SiTrackerBarrelHits">
-      <segmentation type="CartesianGridXY" grid_size_x="0.10*mm" grid_size_y="0.50*mm" />
-      <id>system:8,barrel:2,layer:4,module:12,sensor:2,x:32:-16,y:-16</id>
+      <segmentation type="CartesianGridYZ" grid_size_y="0.10*mm" grid_size_z="0.50*mm" />
+      <id>system:8,barrel:2,layer:4,module:12,sensor:2,y:32:-16,z:-16</id>
     </readout>
     <readout name="SiTrackerEndcapHits">
       <segmentation type="CartesianGridXY" grid_size_x="0.10*mm" grid_size_y="0.50*mm" />