diff --git a/SimG4CMS/Forward/interface/MtdHitCategory.h b/SimG4CMS/Forward/interface/MtdHitCategory.h
new file mode 100644
index 0000000000000..7aa810189b979
--- /dev/null
+++ b/SimG4CMS/Forward/interface/MtdHitCategory.h
@@ -0,0 +1,13 @@
+#ifndef SimG4CMSForward_MtdHitCategory_h
+#define SimG4CMSForward_MtdHitCategory_h
+
+namespace MtdHitCategory {
+  static constexpr unsigned int k_idsecOffset = 1;
+  static constexpr unsigned int k_idloopOffset = 2;
+  static constexpr unsigned int k_idFromCaloOffset = 3;
+  static constexpr unsigned int k_idETLfromBack = 4;
+  static constexpr unsigned int n_categories =
+      std::max({k_idsecOffset, k_idloopOffset, k_idFromCaloOffset, k_idETLfromBack});
+};  // namespace MtdHitCategory
+
+#endif
diff --git a/SimG4CMS/Forward/interface/MtdSD.h b/SimG4CMS/Forward/interface/MtdSD.h
index d58c5e220bcc8..19d651fb84996 100644
--- a/SimG4CMS/Forward/interface/MtdSD.h
+++ b/SimG4CMS/Forward/interface/MtdSD.h
@@ -2,6 +2,8 @@
 #define SimG4CMSForward_MtdSD_h
 
 #include "SimG4CMS/Forward/interface/TimingSD.h"
+#include "SimG4CMS/Forward/interface/MtdHitCategory.h"
+
 #include "FWCore/Framework/interface/Frameworkfwd.h"
 #include "FWCore/ParameterSet/interface/ParameterSetfwd.h"
 
@@ -30,11 +32,6 @@ class MtdSD : public TimingSD {
   void setHitClassID(const G4Step *) override;
 
 private:
-  static constexpr unsigned int k_idsecOffset = 1;
-  static constexpr unsigned int k_idloopOffset = 2;
-  static constexpr unsigned int k_idFromCaloOffset = 3;
-  static constexpr unsigned int k_idETLfromBack = 4;
-
   double energyCut;
   double energyHistoryCut;
 
diff --git a/SimG4CMS/Forward/src/MtdSD.cc b/SimG4CMS/Forward/src/MtdSD.cc
index 4ef7dc731104e..800a78d929257 100644
--- a/SimG4CMS/Forward/src/MtdSD.cc
+++ b/SimG4CMS/Forward/src/MtdSD.cc
@@ -16,6 +16,8 @@
 
 #include <iostream>
 
+using namespace MtdHitCategory;
+
 //-------------------------------------------------------------------
 MtdSD::MtdSD(const std::string& name,
              const SensitiveDetectorCatalog& clg,
diff --git a/SimGeneral/CaloAnalysis/plugins/BuildFile.xml b/SimGeneral/CaloAnalysis/plugins/BuildFile.xml
index 3300315764d4a..7b1458cd095ba 100644
--- a/SimGeneral/CaloAnalysis/plugins/BuildFile.xml
+++ b/SimGeneral/CaloAnalysis/plugins/BuildFile.xml
@@ -23,6 +23,7 @@
 <use name="Geometry/HcalCommonData"/>
 <use name="Geometry/MTDGeometryBuilder"/>
 <use name="Geometry/MTDNumberingBuilder"/>
+<use name="SimG4CMS/Forward"/>
 
 <library file="*.cc" name="SimGeneralCaloAnalysisPlugins">
   <flags EDM_PLUGIN="1"/>
diff --git a/SimGeneral/CaloAnalysis/plugins/MtdTruthAccumulator.cc b/SimGeneral/CaloAnalysis/plugins/MtdTruthAccumulator.cc
index 0cc0f9196430e..930a1b5daec5e 100644
--- a/SimGeneral/CaloAnalysis/plugins/MtdTruthAccumulator.cc
+++ b/SimGeneral/CaloAnalysis/plugins/MtdTruthAccumulator.cc
@@ -59,6 +59,8 @@
 #include "Geometry/MTDGeometryBuilder/interface/ProxyMTDTopology.h"
 #include "Geometry/MTDGeometryBuilder/interface/RectangularMTDTopology.h"
 
+#include "SimG4CMS/Forward/interface/MtdHitCategory.h"
+
 #include <CLHEP/Units/SystemOfUnits.h>
 
 namespace {
@@ -187,7 +189,7 @@ namespace {
       if (!vertex_property.simTrack)
         return;
       // -- loop over possible trackIdOffsets to save also sim clusters from non-direct hits
-      for (unsigned int offset = 0; offset < 4; offset++) {
+      for (unsigned int offset = 0; offset < MtdHitCategory::n_categories + 1; offset++) {
         auto trackIdx = vertex_property.simTrack->trackId();
         trackIdx += offset * (static_cast<int>(PSimHit::k_tidOffset));
         IfLogDebug(DEBUG, messageCategoryGraph_)