diff --git a/options/reconstruction.py b/options/reconstruction.py
index 76b12581a03a4623958e8d63e93f7647c1b2e953..0cbf44dd303a9caf4e063389cc10f4753a9ad8ad 100644
--- a/options/reconstruction.py
+++ b/options/reconstruction.py
@@ -194,8 +194,10 @@ algorithms.append(ci_ecal_reco)
 ci_ecal_merger = CalHitsMerger("ci_ecal_merger",
         inputHitCollection=ci_ecal_reco.outputHitCollection,
         outputHitCollection="EcalEndcapPRecMergedHits",
-        fields=["layer", "slice"],
-        fieldRefNumbers=[1, 0],
+        fields=["fiber_x", "fiber_y"],
+        fieldRefNumbers=[1, 1],
+        # fields=["layer", "slice"],
+        # fieldRefNumbers=[1, 0],
         readoutClass="EcalEndcapPHits")
 algorithms.append(ci_ecal_merger)