diff --git a/src/musrt0.cpp b/src/musrt0.cpp
index c2694a754..55ce05616 100644
--- a/src/musrt0.cpp
+++ b/src/musrt0.cpp
@@ -146,6 +146,9 @@ Int_t musrt0_getMaxBin(const PDoubleVector *data)
   Int_t maxBin = -1;
   Double_t maxData = -999;
 
+  if (data == nullptr)
+    return maxBin;
+
   for (UInt_t i=0; i<data->size(); i++) {
     if (data->at(i) > maxData) {
       maxData = data->at(i);
@@ -221,7 +224,7 @@ Int_t main(Int_t argc, Char_t *argv[])
       return PMUSR_SUCCESS;
     } else if (strstr(argv[i], ".msr")) { // check for filename
       if (strlen(filename) == 0) {
-        strcpy(filename, argv[i]);
+        strncpy(filename, argv[i], sizeof(filename));
       } else {
         std::cout << std::endl << "**ERROR** only one file name allowed." << std::endl;
         show_syntax = true;
@@ -816,7 +819,7 @@ Int_t main(Int_t argc, Char_t *argv[])
             musrT0Data.SetCmdTag(PMUSRT0_GET_T0_DATA_AND_BKG_RANGE);
             // execute cmd
             if (!musrt0_item(app, msrHandler.get(), musrT0Data, 0, timeout)) {
-              exit(0);
+              return 0;
             }
           } else {
             if ((runList->at(i).GetRunNameSize() > 1) && (runList->at(i).GetForwardHistoNoSize() == 1)) { // addruns / no grouping
@@ -842,7 +845,7 @@ Int_t main(Int_t argc, Char_t *argv[])
                 // feed necessary data
                 musrT0Data.SetAddRunIdx(j); // addruns
                 if (!musrt0_item(app, msrHandler.get(), musrT0Data, j, timeout)) {
-                  exit(0);
+                  return 0;
                 }
               }
             } else if ((runList->at(i).GetRunNameSize() == 1) && (runList->at(i).GetForwardHistoNoSize() > 1)) { // no addruns / grouping
@@ -868,7 +871,7 @@ Int_t main(Int_t argc, Char_t *argv[])
                 // feed necessary data
                 musrT0Data.SetHistoNoIdx(j);
                 if (!musrt0_item(app, msrHandler.get(), musrT0Data, 0, timeout)) {
-                  exit(0);
+                  return 0;
                 }
               }
             } else { // addruns / grouping
@@ -896,7 +899,7 @@ Int_t main(Int_t argc, Char_t *argv[])
                   // feed necessary data
                   musrT0Data.SetHistoNoIdx(k);
                   if (!musrt0_item(app, msrHandler.get(), musrT0Data, j, timeout)) {
-                    exit(0);
+                    return 0;
                   }
                 }
               }
@@ -911,7 +914,7 @@ Int_t main(Int_t argc, Char_t *argv[])
               }
             }
             if (!musrt0_item(app, msrHandler.get(), musrT0Data, 0, timeout)) {
-              exit(0);
+              return 0;
             }
           }
           break;
@@ -939,7 +942,7 @@ Int_t main(Int_t argc, Char_t *argv[])
             musrT0Data.SetCmdTag(PMUSRT0_GET_T0_DATA_AND_BKG_RANGE);
             // execute cmd
             if (!musrt0_item(app, msrHandler.get(), musrT0Data, 0, timeout)) {
-              exit(0);
+              return 0;
             }
             // feed necessary data backward
             musrT0Data.InitData();
@@ -961,7 +964,7 @@ Int_t main(Int_t argc, Char_t *argv[])
             musrT0Data.SetCmdTag(PMUSRT0_GET_T0_DATA_AND_BKG_RANGE);
             // execute cmd
             if (!musrt0_item(app, msrHandler.get(), musrT0Data, 0, timeout)) {
-              exit(0);
+              return 0;
             }
           } else {
             // get t0's
@@ -988,7 +991,7 @@ Int_t main(Int_t argc, Char_t *argv[])
                 // feed necessary data
                 musrT0Data.SetAddRunIdx(j); // addruns
                 if (!musrt0_item(app, msrHandler.get(), musrT0Data, j, timeout)) {
-                  exit(0);
+                  return 0;
                 }
               }
               // feed necessary backward data
@@ -1013,7 +1016,7 @@ Int_t main(Int_t argc, Char_t *argv[])
                 // feed necessary data
                 musrT0Data.SetAddRunIdx(j); // addruns
                 if (!musrt0_item(app, msrHandler.get(), musrT0Data, j, timeout)) {
-                  exit(0);
+                  return 0;
                 }
               }
             } else if ((runList->at(i).GetRunNameSize() == 1) && (runList->at(i).GetForwardHistoNoSize() > 1)) { // no addruns / grouping
@@ -1039,7 +1042,7 @@ Int_t main(Int_t argc, Char_t *argv[])
                 // feed necessary data
                 musrT0Data.SetHistoNoIdx(j);
                 if (!musrt0_item(app, msrHandler.get(), musrT0Data, 0, timeout)) {
-                  exit(0);
+                  return 0;
                 }
               }
               // feed necessary backward data
@@ -1064,7 +1067,7 @@ Int_t main(Int_t argc, Char_t *argv[])
                 // feed necessary data
                 musrT0Data.SetHistoNoIdx(j);
                 if (!musrt0_item(app, msrHandler.get(), musrT0Data, 0, timeout)) {
-                  exit(0);
+                  return 0;
                 }
               }
             } else { // addruns / grouping
@@ -1092,7 +1095,7 @@ Int_t main(Int_t argc, Char_t *argv[])
                   // feed necessary data
                   musrT0Data.SetHistoNoIdx(k);
                   if (!musrt0_item(app, msrHandler.get(), musrT0Data, j, timeout)) {
-                    exit(0);
+                    return 0;
                   }
                 }
               }
@@ -1120,7 +1123,7 @@ Int_t main(Int_t argc, Char_t *argv[])
                   // feed necessary data
                   musrT0Data.SetHistoNoIdx(k);
                   if (!musrt0_item(app, msrHandler.get(), musrT0Data, j, timeout)) {
-                    exit(0);
+                    return 0;
                   }
                 }
               }
@@ -1137,12 +1140,12 @@ Int_t main(Int_t argc, Char_t *argv[])
             musrT0Data.SetHistoNo(forwardHistos);
             musrT0Data.SetDetectorTag(PMUSRT0_FORWARD);
             if (!musrt0_item(app, msrHandler.get(), musrT0Data, 0, timeout)) {
-              exit(0);
+              return 0;
             }
             musrT0Data.SetHistoNo(backwardHistos);
             musrT0Data.SetDetectorTag(PMUSRT0_BACKWARD);
             if (!musrt0_item(app, msrHandler.get(), musrT0Data, 0, timeout)) {
-              exit(0);
+              return 0;
             }
           }
           break;
@@ -1166,7 +1169,8 @@ Int_t main(Int_t argc, Char_t *argv[])
   // copy mlog-file -> msr-file
   TString fln = TString(filename);
   Char_t ext[32];
-  strcpy(ext, ".mlog");
+  memset(ext, '\0', sizeof(ext));
+  strncpy(ext, ".mlog", sizeof(ext));
   fln.ReplaceAll(".msr", 4, ext, strlen(ext));
   gSystem->CopyFile(fln.Data(), filename, kTRUE);
   // copy __temp.msr -> mlog-file