diff --git a/JobConfig/cosmic/cosmic_s1_dsstops.fcl b/JobConfig/cosmic/cosmic_s1_dsstops.fcl
index 5a82c54dc8..1c4bc6545a 100644
--- a/JobConfig/cosmic/cosmic_s1_dsstops.fcl
+++ b/JobConfig/cosmic/cosmic_s1_dsstops.fcl
@@ -115,7 +115,7 @@ services :
    TFileService          : { }
    RandomNumberGenerator : {defaultEngineKind: "MixMaxRng" }
 
-   GeometryService        : { inputFile      : "JobConfig/cosmic/geom_cosmic.txt" }
+   GeometryService        : { inputFile      : "JobConfig/cosmic/geom_cosmic_PhaseI.txt" }
    ConditionsService      : { conditionsfile : "Mu2eG4/test/conditions_01.txt"      }
    GlobalConstantsService : { inputFile      : "Mu2eG4/test/globalConstants_01.txt" }
    G4Helper               : { }
diff --git a/JobConfig/cosmic/geom_cosmic_PhaseI.txt b/JobConfig/cosmic/geom_cosmic_PhaseI.txt
new file mode 100644
index 0000000000..4288c1a3c0
--- /dev/null
+++ b/JobConfig/cosmic/geom_cosmic_PhaseI.txt
@@ -0,0 +1,17 @@
+#include "Mu2eG4/geom/geom_2019_PhaseI_hayman_v2.txt"
+
+// Cosmis s1 samples for CD3 were generated with the TDR target geometry.
+// Keep using it for the subsequent stages.
+
+double world.minimalMargin.xmin = 500000;
+double world.minimalMargin.xmax = 500000;
+double world.minimalMargin.zmin = 500000;
+double world.minimalMargin.zmax = 500000;
+
+string dirt.beamline.berm.material = "G4_AIR";
+
+//
+// This tells emacs to view this file in c++ mode.
+// Local Variables:
+// mode:c++
+// End: