diff --git a/src/classes/PRunBase.cpp b/src/classes/PRunBase.cpp
index 8be39ebef..3b51cb10c 100644
--- a/src/classes/PRunBase.cpp
+++ b/src/classes/PRunBase.cpp
@@ -205,7 +205,7 @@ void PRunBase::DeadTimeCorrection(std::vector<PDoubleVector> &histos, PUIntVecto
         Int_t gf = runData->GetNumberOfGoodFrames();
         std::vector<float> t_dt = runData->GetDeadTimeParam();
         for (UInt_t j=0; j<histos[i].size(); j++) {
-          n_true = histos[i][j] / (1.0 - histos[i][j] * t_dt[histoNo[i]] / (gf * fTimeResolution));
+          n_true = histos[i][j] / (1.0 - histos[i][j] * t_dt[histoNo[i]-1] / (gf * fTimeResolution));
           histos[i][j] = n_true;
         }
       }