diff --git a/src/BarrelCalorimeter_geo.cpp b/src/BarrelCalorimeter_geo.cpp
index c419fe779e3bee187345a161e6ef90c66690c448..d62e0799e46171c5229bf6354e301a86abab3b83 100644
--- a/src/BarrelCalorimeter_geo.cpp
+++ b/src/BarrelCalorimeter_geo.cpp
@@ -134,7 +134,7 @@ static Ref_t create_detector(Detector& description, xml_h e, SensitiveDetector s
     // Parameters for computing the layer X dimension:
     double stave_z  = trd_y1;
     double tan_hphi = std::tan(hphi);
-    double l_dim_x  = trd_x2; // Starting X dimension for the layer.
+    double l_dim_x  = trd_x1; // Starting X dimension for the layer.
 
     // Loop over the sets of layer elements in the detector.
     int l_num = 1;