diff --git a/ChangeLog b/ChangeLog
index c326ee8b..d74fd7ae 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -11,6 +11,7 @@ NEW any2many: an attempt to write the universial musr-data-file converter. Just
 NEW musrt0: added the possibility to show the t0 saved in the data file 's'. Furthermore added the option
     --getT0FromPromptPeak, -g with <firstGoodBinOffset>: will, in non-interactive mode estimate the t0's from 
     the prompt peak and write it into the msr-file (MUSR-133).
+FIXED background range correction, such that it is a multiple of the proton cycle time
 FIXED linking of BMWlibs on Cygwin
 FIXED various bugs in msr2data
 FIXED 2 little annoying problems: (i) now it is possible to zoom down to the single bin in musrview. 
diff --git a/src/classes/PRunAsymmetry.cpp b/src/classes/PRunAsymmetry.cpp
index 0a3ba780..cefdc364 100644
--- a/src/classes/PRunAsymmetry.cpp
+++ b/src/classes/PRunAsymmetry.cpp
@@ -32,6 +32,7 @@
 #include <stdio.h>
 
 #include <iostream>
+using namespace std;
 
 #include "PMusr.h"
 #include "PRunAsymmetry.h"
@@ -316,6 +317,8 @@ Bool_t PRunAsymmetry::PrepareData()
 
   // keep the time resolution in (us)
   fTimeResolution = runData->GetTimeResolution()/1.0e3;
+  cout.precision(8);
+  cout << endl << ">> PRunSingleHisto::PrepareData(): time resolution=" << fixed << runData->GetTimeResolution() << "(ns)" << endl;
 
   // collect histogram numbers
   PUIntVector forwardHistoNo;
@@ -690,9 +693,10 @@ Bool_t PRunAsymmetry::SubtractEstimatedBkg()
   // calculate proper background range
   for (UInt_t i=0; i<2; i++) {
     if (beamPeriod != 0.0) {
-      Double_t beamPeriodBins = beamPeriod/fRunInfo->GetPacking();
-      UInt_t periods = (UInt_t)((Double_t)(end[i] - start[i] + 1) / beamPeriodBins);
-      end[i] = start[i] + (UInt_t)round((Double_t)periods*beamPeriodBins);
+      Double_t timeBkg = (Double_t)(end-start)*(fTimeResolution*fRunInfo->GetPacking()); // length of the background intervall in time
+      UInt_t fullCycles = (UInt_t)(timeBkg/beamPeriod); // how many proton beam cylces can be placed within the proposed background intervall
+      // correct the end of the background intervall such that the background is as close as possible to a multiple of the proton cylce
+      end[i] = start[i] + (UInt_t) ((fullCycles*beamPeriod)/(fTimeResolution*fRunInfo->GetPacking()));
       cout << "PRunAsymmetry::SubtractEstimatedBkg(): Background " << start[i] << ", " << end[i] << endl;
       if (end[i] == start[i])
         end[i] = fRunInfo->GetBkgRange(2*i+1);
diff --git a/src/classes/PRunSingleHisto.cpp b/src/classes/PRunSingleHisto.cpp
index 9c21a470..a0748e86 100644
--- a/src/classes/PRunSingleHisto.cpp
+++ b/src/classes/PRunSingleHisto.cpp
@@ -31,6 +31,7 @@
 
 #include <iostream>
 #include <fstream>
+using namespace std;
 
 #include "PMusr.h"
 #include "PRunSingleHisto.h"
@@ -494,6 +495,8 @@ Bool_t PRunSingleHisto::PrepareData()
 
   // keep the time resolution in (us)
   fTimeResolution = runData->GetTimeResolution()/1.0e3;
+  cout.precision(8);
+  cout << endl << ">> PRunSingleHisto::PrepareData(): time resolution=" << fixed << runData->GetTimeResolution() << "(ns)" << endl;
 
   if (fHandleTag == kFit)
     success = PrepareFitData(runData, histoNo[0]);
@@ -1137,9 +1140,10 @@ Bool_t PRunSingleHisto::EstimateBkg(UInt_t histoNo)
 
   // calculate proper background range
   if (beamPeriod != 0.0) {
-    Double_t beamPeriodBins = beamPeriod/fRunInfo->GetPacking();
-    UInt_t periods = (UInt_t)((Double_t)(end - start + 1) / beamPeriodBins);
-    end = start + (UInt_t)round((Double_t)periods*beamPeriodBins);
+    Double_t timeBkg = (Double_t)(end-start)*(fTimeResolution*fRunInfo->GetPacking()); // length of the background intervall in time
+    UInt_t fullCycles = (UInt_t)(timeBkg/beamPeriod); // how many proton beam cylces can be placed within the proposed background intervall
+    // correct the end of the background intervall such that the background is as close as possible to a multiple of the proton cylce
+    end = start + (UInt_t) ((fullCycles*beamPeriod)/(fTimeResolution*fRunInfo->GetPacking()));
     cout << endl << "PRunSingleHisto::EstimatBkg(): Background " << start << ", " << end;
     if (end == start)
       end = fRunInfo->GetBkgRange(1);