diff --git a/sim/detectors/trd/CbmTrdDigitizer.cxx b/sim/detectors/trd/CbmTrdDigitizer.cxx
index 6e71dfa8be986a2f03a6bfa70fff5a43693aabbc..023069fa2dc8a17bdd6f3edc496d081bbf9165fb 100644
--- a/sim/detectors/trd/CbmTrdDigitizer.cxx
+++ b/sim/detectors/trd/CbmTrdDigitizer.cxx
@@ -204,7 +204,7 @@ void CbmTrdDigitizer::Exec(Option_t*)
     else
       mod = imod->second;
     mod->SetLinkId(fCurrentInput, fCurrentMCEntry, iPoint);
-    Double_t gamma = TMath::Sqrt(1 + TMath::Power(track->GetP() / (3.e8 * track->GetMass()), 2));
+    Double_t gamma = TMath::Sqrt(1 + TMath::Power(track->GetP() / (track->GetMass()), 2));
     mod->SetGamma(gamma);
     mod->MakeDigi(point, fCurrentEventTime, TMath::Abs(track->GetPdgCode()) == 11);
   }