diff --git a/src/classes/PFourier.cpp b/src/classes/PFourier.cpp
index b9484d23..7b3e5a82 100644
--- a/src/classes/PFourier.cpp
+++ b/src/classes/PFourier.cpp
@@ -99,7 +99,6 @@ PFourier::PFourier(TH1F *data, Int_t unitTag, Double_t startTime, Double_t endTi
 
   // calculate start and end bin
   fNoOfData = (UInt_t)((fEndTime-fStartTime)/fTimeResolution);
-  cout << "debug> fNoOfData=" << fNoOfData << endl;
 
   // check if zero padding is whished
   if (fZeroPaddingPower > 0) {
@@ -554,22 +553,27 @@ TH1F* PFourier::GetPhaseFourier(const Double_t scale)
 void PFourier::PrepareFFTwInputData(UInt_t apodizationTag)
 {
   // 1st find t==0. fData start at times t<0!!
-  UInt_t t0bin = -1;
+  Int_t t0bin = -1;
   for (Int_t i=1; i<fData->GetNbinsX(); i++) {
     if (fData->GetBinCenter(i) >= 0.0) {
       t0bin = i;
       break;
     }
   }
-  cout << "debug> t0bin=" << t0bin << ", fNoOfData=" << fNoOfData << ", fNoOfBins=" << fNoOfBins << endl;
+
+  // find the bin of the start time
+  Int_t ival = static_cast<Int_t>(fStartTime/fTimeResolution) + t0bin;
+  UInt_t start = 1;
+  if (ival > 0) { // start time > 0
+    start = static_cast<UInt_t>(ival);
+  }
 
   Double_t mean = 0.0;
   if (fDCCorrected) {
-    for (UInt_t i=t0bin; i<fNoOfData; i++) {
+    for (UInt_t i=start; i<fNoOfData; i++) {
       mean += fData->GetBinContent(i);
     }
-    mean /= (Double_t)(fNoOfData-t0bin);
-    cout << "debug> mean=" << mean << endl;
+    mean /= (Double_t)(fNoOfData-start);
   }  
 
   // 2nd fill fIn