diff --git a/src/addRun.cpp b/src/addRun.cpp
index 9e361615..5c5ada53 100644
--- a/src/addRun.cpp
+++ b/src/addRun.cpp
@@ -34,6 +34,7 @@
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
+#include <string>
 
 #include <iostream>
 #include <fstream>
@@ -162,24 +163,22 @@ bool addRun_checkFormat(std::string &format) {
 bool addRun_readInputFiles(const std::string fileName, std::vector<PAddRunInfo> &infoVec)
 {
   PAddRunInfo info;
-  char buf[256], str[256];
+  char str[256];
   std::ifstream fin(fileName.c_str(), std::ifstream::in);
   std::string line;
   char *tok{nullptr};
   int status, ival;
   bool lastWasFile{false};
-  memset(buf, '\0', sizeof(buf));
   memset(str, '\0', sizeof(str));
-  while (fin.good()) {
-    fin.getline(buf, 256);
-    line = buf;
+  // read into a std::string: a fixed size line buffer silently drops the rest of
+  // the input file as soon as one line (e.g. a long data-file path) exceeds it.
+  while (std::getline(fin, line)) {
     boost::trim_left(line);
     if (line.empty())
       continue;
     if (line[0] == '%')
       continue;
-    strncpy(buf, line.c_str(), sizeof(buf));
-    tok = strtok(buf, " ");
+    tok = strtok(line.data(), " "); // strtok tokenises in place, line stays the owner
     if (!strcmp(tok, "file")) {
       if (lastWasFile) {
         infoVec.push_back(info);
@@ -198,7 +197,7 @@ bool addRun_readInputFiles(const std::string fileName, std::vector<PAddRunInfo>
       lastWasFile = true;
     } else if (!strcmp(tok, "t0")) {
       while ((tok = strtok(NULL, ",")) != NULL) {
-        status = sscanf(tok, "%d%s", &ival, str);
+        status = sscanf(tok, "%d%255s", &ival, str);
         if (status != 1) {
           std::cerr << std::endl;
           std::cerr << "**ERROR** found t0 argument '" << tok << "' which is not a number." << std::endl;
@@ -541,20 +540,19 @@ int main(int argc, char *argv[])
   }
 
   // read startup file
-  char startup_path_name[128];
-  memset(startup_path_name, '\0', sizeof(startup_path_name));
+  std::string startup_path_name{};
   std::unique_ptr<TSAXParser> saxParser = std::make_unique<TSAXParser>();
   std::unique_ptr<PStartupHandler> startupHandler = std::make_unique<PStartupHandler>();
   if (!startupHandler->StartupFileFound()) {
     std::cerr << std::endl << ">> addRun **WARNING** couldn't find " << startupHandler->GetStartupFilePath().Data();
     std::cerr << std::endl;
   } else {
-    strncpy(startup_path_name, startupHandler->GetStartupFilePath().Data(), sizeof(startup_path_name));
+    startup_path_name = startupHandler->GetStartupFilePath().Data();
     saxParser->ConnectToHandler("PStartupHandler", startupHandler.get());
     //status = saxParser->ParseFile(startup_path_name);
     // parsing the file as above seems to lead to problems in certain environments;
     // use the parseXmlFile function instead (see PStartupHandler.cpp for the definition)
-    status = parseXmlFile(saxParser.get(), startup_path_name);
+    status = parseXmlFile(saxParser.get(), startup_path_name.c_str());
     // check for parse errors
     if (status) { // error
       std::cerr << std::endl << ">> addRun **WARNING** Reading/parsing musrfit_startup.xml failed.";
diff --git a/src/any2many.cpp b/src/any2many.cpp
index 67121939..f3f78dfd 100644
--- a/src/any2many.cpp
+++ b/src/any2many.cpp
@@ -34,6 +34,7 @@
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
+#include <string>
 
 #include <iostream>
 #include <fstream>
@@ -498,20 +499,19 @@ int main(int argc, char *argv[])
   }
 
   // read startup file
-  char startup_path_name[128];
-  memset(startup_path_name, '\0', sizeof(startup_path_name));
+  std::string startup_path_name{};
   std::unique_ptr<TSAXParser> saxParser = std::make_unique<TSAXParser>();
   std::unique_ptr<PStartupHandler> startupHandler = std::make_unique<PStartupHandler>();
   if (!startupHandler->StartupFileFound()) {
     std::cerr << std::endl << ">> any2many **WARNING** couldn't find " << startupHandler->GetStartupFilePath().Data();
     std::cerr << std::endl;
   } else {
-    strncpy(startup_path_name, startupHandler->GetStartupFilePath().Data(), sizeof(startup_path_name));
+    startup_path_name = startupHandler->GetStartupFilePath().Data();
     saxParser->ConnectToHandler("PStartupHandler", startupHandler.get());
     //status = saxParser->ParseFile(startup_path_name);
     // parsing the file as above seems to lead to problems in certain environments;
     // use the parseXmlFile function instead (see PStartupHandler.cpp for the definition)
-    status = parseXmlFile(saxParser.get(), startup_path_name);
+    status = parseXmlFile(saxParser.get(), startup_path_name.c_str());
     // check for parse errors
     if (status) { // error
       std::cerr << std::endl << ">> any2many **WARNING** Reading/parsing musrfit_startup.xml failed.";
diff --git a/src/classes/PFourierCanvas.cpp b/src/classes/PFourierCanvas.cpp
index 20276d2c..f45c4bf3 100644
--- a/src/classes/PFourierCanvas.cpp
+++ b/src/classes/PFourierCanvas.cpp
@@ -146,7 +146,13 @@ PFourierCanvas::PFourierCanvas(std::vector<PFourier*> &fourier, PIntVector dataS
     rand.SetSeed(i);
     style = 20+static_cast<Int_t>(rand.Integer(10));
     fMarkerList.push_back(style);
-    color = TColor::GetColor(static_cast<Int_t>(rand.Integer(255)), static_cast<Int_t>(rand.Integer(255)), static_cast<Int_t>(rand.Integer(255)));
+    // the rgb values need to be drawn into separate variables first: the evaluation order of
+    // function arguments is unspecified in C++, hence calling rand.Integer() three times within
+    // the argument list would yield compiler dependent (r,g,b) permutations.
+    Int_t r = static_cast<Int_t>(rand.Integer(255));
+    Int_t g = static_cast<Int_t>(rand.Integer(255));
+    Int_t b = static_cast<Int_t>(rand.Integer(255));
+    color = TColor::GetColor(r, g, b);
     fColorList.push_back(color);
   }
 
@@ -226,7 +232,13 @@ PFourierCanvas::PFourierCanvas(std::vector<PFourier*> &fourier, PIntVector dataS
   }
   for (UInt_t i=static_cast<UInt_t>(fColorList.size()); i<fourier.size(); i++) {
     rand.SetSeed(i);
-    color = TColor::GetColor(static_cast<Int_t>(rand.Integer(255)), static_cast<Int_t>(rand.Integer(255)), static_cast<Int_t>(rand.Integer(255)));
+    // the rgb values need to be drawn into separate variables first: the evaluation order of
+    // function arguments is unspecified in C++, hence calling rand.Integer() three times within
+    // the argument list would yield compiler dependent (r,g,b) permutations.
+    Int_t r = static_cast<Int_t>(rand.Integer(255));
+    Int_t g = static_cast<Int_t>(rand.Integer(255));
+    Int_t b = static_cast<Int_t>(rand.Integer(255));
+    color = TColor::GetColor(r, g, b);
     fColorList.push_back(color);
   }
 
diff --git a/src/classes/PMusrCanvas.cpp b/src/classes/PMusrCanvas.cpp
index 58a6ab1d..acf5a357 100644
--- a/src/classes/PMusrCanvas.cpp
+++ b/src/classes/PMusrCanvas.cpp
@@ -1527,7 +1527,7 @@ void PMusrCanvas::WindowClosed()
  * \param fileName file name under which the canvas shall be saved.
  * \param graphicsFormat One of the supported graphics formats.
  */
-void PMusrCanvas::SaveGraphicsAndQuit(Char_t *fileName, Char_t *graphicsFormat)
+void PMusrCanvas::SaveGraphicsAndQuit(const Char_t *fileName, const Char_t *graphicsFormat)
 {
   std::cout << std::endl << ">> SaveGraphicsAndQuit: will dump the canvas into a graphics output file (" << graphicsFormat << ") ..."<< std::endl;
 
@@ -2925,7 +2925,13 @@ void PMusrCanvas::HandleDataSet(UInt_t plotNo, UInt_t runNo, PRunData *data)
     dataHisto->SetLineColor(fColorList[plotNo]);
   } else {
     TRandom rand(plotNo);
-    Int_t color = TColor::GetColor((Int_t)rand.Integer(255), (Int_t)rand.Integer(255), (Int_t)rand.Integer(255));
+    // the rgb values need to be drawn into separate variables first: the evaluation order of
+    // function arguments is unspecified in C++, hence calling rand.Integer() three times within
+    // the argument list would yield compiler dependent (r,g,b) permutations.
+    Int_t r = (Int_t)rand.Integer(255);
+    Int_t g = (Int_t)rand.Integer(255);
+    Int_t b = (Int_t)rand.Integer(255);
+    Int_t color = TColor::GetColor(r, g, b);
     dataHisto->SetMarkerColor(color);
     dataHisto->SetLineColor(color);
   }
@@ -3058,7 +3064,13 @@ void PMusrCanvas::HandleDataSet(UInt_t plotNo, UInt_t runNo, PRunData *data)
     theoHisto->SetLineColor(fColorList[plotNo]);
   } else {
     TRandom rand(plotNo);
-    Int_t color = TColor::GetColor((Int_t)rand.Integer(255), (Int_t)rand.Integer(255), (Int_t)rand.Integer(255));
+    // the rgb values need to be drawn into separate variables first: the evaluation order of
+    // function arguments is unspecified in C++, hence calling rand.Integer() three times within
+    // the argument list would yield compiler dependent (r,g,b) permutations.
+    Int_t r = (Int_t)rand.Integer(255);
+    Int_t g = (Int_t)rand.Integer(255);
+    Int_t b = (Int_t)rand.Integer(255);
+    Int_t color = TColor::GetColor(r, g, b);
     theoHisto->SetLineColor(color);
   }
 
@@ -3108,7 +3120,13 @@ void PMusrCanvas::HandleNonMusrDataSet(UInt_t plotNo, UInt_t runNo, PRunData *da
     dataHisto->SetLineColor(fColorList[plotNo]);
   } else {
     TRandom rand(plotNo);
-    Int_t color = TColor::GetColor((Int_t)rand.Integer(255), (Int_t)rand.Integer(255), (Int_t)rand.Integer(255));
+    // the rgb values need to be drawn into separate variables first: the evaluation order of
+    // function arguments is unspecified in C++, hence calling rand.Integer() three times within
+    // the argument list would yield compiler dependent (r,g,b) permutations.
+    Int_t r = (Int_t)rand.Integer(255);
+    Int_t g = (Int_t)rand.Integer(255);
+    Int_t b = (Int_t)rand.Integer(255);
+    Int_t color = TColor::GetColor(r, g, b);
     dataHisto->SetMarkerColor(color);
     dataHisto->SetLineColor(color);
   }
@@ -3138,7 +3156,13 @@ void PMusrCanvas::HandleNonMusrDataSet(UInt_t plotNo, UInt_t runNo, PRunData *da
     theoHisto->SetLineColor(fColorList[plotNo]);
   } else {
     TRandom rand(plotNo);
-    Int_t color = TColor::GetColor((Int_t)rand.Integer(255), (Int_t)rand.Integer(255), (Int_t)rand.Integer(255));
+    // the rgb values need to be drawn into separate variables first: the evaluation order of
+    // function arguments is unspecified in C++, hence calling rand.Integer() three times within
+    // the argument list would yield compiler dependent (r,g,b) permutations.
+    Int_t r = (Int_t)rand.Integer(255);
+    Int_t g = (Int_t)rand.Integer(255);
+    Int_t b = (Int_t)rand.Integer(255);
+    Int_t color = TColor::GetColor(r, g, b);
     theoHisto->SetLineColor(color);
   }
 
diff --git a/src/dump_header.cpp b/src/dump_header.cpp
index 7561ca75..1897c33d 100644
--- a/src/dump_header.cpp
+++ b/src/dump_header.cpp
@@ -611,10 +611,10 @@ int dump_header_mud(const std::string fileName, const bool counts)
   char   str[1024];
   int    success;
 
-  char fln[256];
-  memset(fln, '\0', sizeof(fln));
-  strncpy(fln, fileName.c_str(), sizeof(fln));
-  fh = MUD_openRead(fln, &type);
+  // MUD_openRead() takes a non-const char*, hence the mutable copy. It must not
+  // be a fixed size buffer: paths longer than its size would silently truncate.
+  std::string fln(fileName);
+  fh = MUD_openRead(fln.data(), &type);
   if (fh == -1) {
     std::cerr << std::endl << "**ERROR** Couldn't open mud-file " << fileName << ", sorry." << std::endl;
     return 1;
@@ -1019,20 +1019,19 @@ int main(int argc, char *argv[])
 
   // invoke the startup handler in order to get the default search paths to the data files
   // read startup file
-  char startup_path_name[128];
-  memset(startup_path_name, '\0', sizeof(startup_path_name));
+  std::string startup_path_name{};
   std::unique_ptr<TSAXParser> saxParser = std::make_unique<TSAXParser>();
   std::unique_ptr<PStartupHandler> startupHandler = std::make_unique<PStartupHandler>();
   if (!startupHandler->StartupFileFound()) {
     std::cerr << std::endl << ">> musrfit **WARNING** couldn't find " << startupHandler->GetStartupFilePath().Data();
     std::cerr << std::endl;
   } else {
-    strncpy(startup_path_name, startupHandler->GetStartupFilePath().Data(), sizeof(startup_path_name));
+    startup_path_name = startupHandler->GetStartupFilePath().Data();
     saxParser->ConnectToHandler("PStartupHandler", startupHandler.get());
     //status = saxParser->ParseFile(startup_path_name);
     // parsing the file as above seems to lead to problems in certain environments;
     // use the parseXmlFile function instead (see PStartupHandler.cpp for the definition)
-    int status = parseXmlFile(saxParser.get(), startup_path_name);
+    int status = parseXmlFile(saxParser.get(), startup_path_name.c_str());
     // check for parse errors
     if (status) { // error
       std::cerr << std::endl << ">> musrfit **WARNING** Reading/parsing musrfit_startup.xml failed.";
diff --git a/src/include/PMusrCanvas.h b/src/include/PMusrCanvas.h
index 497d5ea2..78a31db2 100644
--- a/src/include/PMusrCanvas.h
+++ b/src/include/PMusrCanvas.h
@@ -350,7 +350,7 @@ class PMusrCanvas : public TObject, public TQObject
     virtual void WindowClosed(); // SLOT
 
     /// Saves canvas to graphics file and emits Done signal
-    virtual void SaveGraphicsAndQuit(Char_t *fileName, Char_t *graphicsFormat);
+    virtual void SaveGraphicsAndQuit(const Char_t *fileName, const Char_t *graphicsFormat);
     /// Exports displayed data to ASCII file
     virtual void ExportData(const Char_t *fileName);
 
diff --git a/src/msr2msr.cpp b/src/msr2msr.cpp
index 6852485c..30b8eca9 100644
--- a/src/msr2msr.cpp
+++ b/src/msr2msr.cpp
@@ -29,6 +29,8 @@
 
 #include <iostream>
 #include <fstream>
+#include <filesystem>
+#include <string>
 
 #include <cctype>
 #include <cstring>
@@ -388,7 +390,7 @@ bool msr2msr_theory(char *str, int &tag, int &noOfAddionalParams)
  *
  * \param str msr-file line
  */
-bool msr2msr_is_comment(char *str)
+bool msr2msr_is_comment(const char *str)
 {
   bool isComment = false;
 
@@ -417,7 +419,7 @@ bool msr2msr_is_comment(char *str)
  *
  * \param str msr-file line
  */
-bool msr2msr_is_whitespace(char *str)
+bool msr2msr_is_whitespace(const char *str)
 {
   bool isWhitespace = true;
 
@@ -440,29 +442,25 @@ bool msr2msr_is_whitespace(char *str)
  * \param str msr-file line
  * \param paramNo parameter number
  */
-void msr2msr_replace(char *str, int paramNo)
+void msr2msr_replace(std::string &str, int paramNo)
 {
-  char temp[128];
-  char no[16];
+  const std::string no{std::to_string(paramNo)};
 
-  memset(temp, 0, sizeof(temp));
+  // build the result in a std::string: the previous fixed size scratch buffer
+  // overflowed for msr-lines longer than its size.
+  std::string temp;
+  temp.reserve(str.length());
 
-  snprintf(no, sizeof(no), "%d", paramNo);
-
-  int j=0;
-  for (unsigned int i=0; i<strlen(str); i++) {
+  for (std::string::size_type i=0; i<str.length(); i++) {
     if (str[i] != '_') {
-      temp[j] = str[i];
-      j++;
-    } else {
-      for (unsigned int k=0; k<strlen(no); k++)
-        temp[j+k] = no[k];
-      j += strlen(no);
+      temp += str[i];
+    } else { // '_x_' placeholder -> parameter number
+      temp += no;
       i += 2;
     }
   }
 
-  strcpy(str, temp);
+  str = temp;
 }
 
 //--------------------------------------------------------------------------
@@ -494,25 +492,23 @@ bool msr2msr_finalize_theory(char *fln, int theoryTag, int noOfAddionalParams)
     return 0;
   }
 
-  char str[256];
+  std::string str;
   int  tag = -1;
   bool success = true;
   int  param = 0;
   int  count = 0;
-  while (!fin.eof() && success) {
-    fin.getline(str, sizeof(str));
-
-    if (strstr(str, "FITPARAMETER")) {
+  while (std::getline(fin, str) && success) {
+    if (str.find("FITPARAMETER") != std::string::npos) {
       tag = MSR_TAG_FITPARAMETER;
-    } else if (strstr(str, "THEORY")) {
+    } else if (str.find("THEORY") != std::string::npos) {
       tag = MSR_TAG_THEORY;
     }
 
-    if ((tag == MSR_TAG_FITPARAMETER) && !strstr(str, "FITPARAMETER")) {
+    if ((tag == MSR_TAG_FITPARAMETER) && (str.find("FITPARAMETER") == std::string::npos)) {
       if ((theoryTag == MSR_THEORY_INTERN_FLD) || (theoryTag == MSR_THEORY_INTERN_BESSEL)) {
-        if (!msr2msr_is_comment(str)) {
+        if (!msr2msr_is_comment(str.c_str())) {
           param++;
-          if (msr2msr_is_whitespace(str)) {
+          if (msr2msr_is_whitespace(str.c_str())) {
             // add needed parameters
             for (int i=0; i<noOfAddionalParams; i++) {
               fout << "        " << param+i << " frac" << i+1 << "       0.333333 0.0        none" << std::endl;
@@ -524,7 +520,7 @@ bool msr2msr_finalize_theory(char *fln, int theoryTag, int noOfAddionalParams)
 
     if (tag == MSR_TAG_THEORY) {
       if ((theoryTag == MSR_THEORY_INTERN_FLD) || (theoryTag == MSR_THEORY_INTERN_BESSEL)) {
-        if (strstr(str, "_x_")) {
+        if (str.find("_x_") != std::string::npos) {
           msr2msr_replace(str, param+count);
           count++;
         }
@@ -539,16 +535,19 @@ bool msr2msr_finalize_theory(char *fln, int theoryTag, int noOfAddionalParams)
   fin.close();
 
 
-  // cp __temp.msr fln
-  snprintf(str, sizeof(str), "cp __temp.msr %s", fln);
-  if (system(str) == -1) {
-    std::cerr << "**ERROR** cmd: " << str << " failed." << std::endl;
+  // cp __temp.msr fln, and rm __temp.msr afterwards. Done via std::filesystem
+  // rather than system(): a shell command assembled in a fixed size buffer would
+  // silently truncate for long paths (and choke on paths containing blanks).
+  std::error_code ec;
+  std::filesystem::copy_file(std::filesystem::path("__temp.msr"), std::filesystem::path(fln),
+                             std::filesystem::copy_options::overwrite_existing, ec);
+  if (ec) {
+    std::cerr << "**ERROR** couldn't copy __temp.msr -> " << fln << ": " << ec.message() << std::endl;
     return false;
   }
-  // rm __temp.msr
-  strcpy(str, "rm __temp.msr");
-  if (system(str) == -1) {
-    std::cerr << "**ERROR** cmd: " << str << " failed." << std::endl;
+  std::filesystem::remove(std::filesystem::path("__temp.msr"), ec);
+  if (ec) {
+    std::cerr << "**ERROR** couldn't remove __temp.msr: " << ec.message() << std::endl;
     return false;
   }
 
@@ -677,9 +676,10 @@ int main(int argc, char *argv[])
 
   // check if conversion seems to be OK
   if (!success) {
-    snprintf(str, sizeof(str), "rm -rf %s", argv[2]);
-    if (system(str) == -1) {
-      std::cerr << "**ERROR** cmd: " << str << " failed." << std::endl;
+    std::error_code ec;
+    std::filesystem::remove_all(std::filesystem::path(argv[2]), ec);
+    if (ec) {
+      std::cerr << "**ERROR** couldn't remove " << argv[2] << ": " << ec.message() << std::endl;
       return 0;
     }
   }
diff --git a/src/musrFT.cpp b/src/musrFT.cpp
index ae8f9e5f..6482110a 100644
--- a/src/musrFT.cpp
+++ b/src/musrFT.cpp
@@ -1020,7 +1020,7 @@ Int_t main(Int_t argc, Char_t *argv[])
   }
 
   // read startup file
-  Char_t startup_path_name[128];
+  std::string startup_path_name{};
   PStartupOptions startup_options;
   startup_options.writeExpectedChisq = false;
   startup_options.estimateN0 = true;
@@ -1030,12 +1030,12 @@ Int_t main(Int_t argc, Char_t *argv[])
     std::cerr << std::endl << ">> musrFT **WARNING** couldn't find " << startupHandler->GetStartupFilePath().Data();
     std::cerr << std::endl;
   } else {
-    strcpy(startup_path_name, startupHandler->GetStartupFilePath().Data());
+    startup_path_name = startupHandler->GetStartupFilePath().Data();
     saxParser->ConnectToHandler("PStartupHandler", startupHandler.get());
     //status = saxParser->ParseFile(startup_path_name);
     // parsing the file as above seems to lead to problems in certain environments;
     // use the parseXmlFile function instead (see PStartupHandler.cpp for the definition)
-    status = parseXmlFile(saxParser.get(), startup_path_name);
+    status = parseXmlFile(saxParser.get(), startup_path_name.c_str());
     // check for parse errors
     if (status) { // error
       std::cerr << std::endl << ">> musrFT **WARNING** Reading/parsing musrfit_startup.xml failed.";
diff --git a/src/musredit_qt5/mupp/plotter/PMuppCanvas.cpp b/src/musredit_qt5/mupp/plotter/PMuppCanvas.cpp
index 4c685fd7..51121707 100644
--- a/src/musredit_qt5/mupp/plotter/PMuppCanvas.cpp
+++ b/src/musredit_qt5/mupp/plotter/PMuppCanvas.cpp
@@ -537,7 +537,13 @@ void PMuppCanvas::UpdateGraphs()
             gg->SetFillColor(kWhite);
           } else { // random choise of the color
             TRandom rand(i+j+k);
-            color = TColor::GetColor((Int_t)rand.Integer(255), (Int_t)rand.Integer(255), (Int_t)rand.Integer(255));
+            // the rgb values need to be drawn into separate variables first: the evaluation order
+            // of function arguments is unspecified in C++, hence calling rand.Integer() three times
+            // within the argument list would yield compiler dependent (r,g,b) permutations.
+            Int_t r = (Int_t)rand.Integer(255);
+            Int_t g = (Int_t)rand.Integer(255);
+            Int_t b = (Int_t)rand.Integer(255);
+            color = TColor::GetColor(r, g, b);
             gg->SetMarkerColor(color);
             gg->SetLineColor(color);
             gg->SetFillColor(kWhite);
diff --git a/src/musredit_qt6/mupp/plotter/PMuppCanvas.cpp b/src/musredit_qt6/mupp/plotter/PMuppCanvas.cpp
index 16aff557..91e06a12 100644
--- a/src/musredit_qt6/mupp/plotter/PMuppCanvas.cpp
+++ b/src/musredit_qt6/mupp/plotter/PMuppCanvas.cpp
@@ -591,7 +591,13 @@ void PMuppCanvas::UpdateGraphs()
             gg->SetFillColor(kWhite);
           } else { // random choise of the color
             TRandom rand(i+j+k);
-            color = TColor::GetColor((Int_t)rand.Integer(255), (Int_t)rand.Integer(255), (Int_t)rand.Integer(255));
+            // the rgb values need to be drawn into separate variables first: the evaluation order
+            // of function arguments is unspecified in C++, hence calling rand.Integer() three times
+            // within the argument list would yield compiler dependent (r,g,b) permutations.
+            Int_t r = (Int_t)rand.Integer(255);
+            Int_t g = (Int_t)rand.Integer(255);
+            Int_t b = (Int_t)rand.Integer(255);
+            color = TColor::GetColor(r, g, b);
             gg->SetMarkerColor(color);
             gg->SetLineColor(color);
             gg->SetFillColor(kWhite);
diff --git a/src/musrfit.cpp b/src/musrfit.cpp
index ceaf781a..61185d49 100644
--- a/src/musrfit.cpp
+++ b/src/musrfit.cpp
@@ -37,7 +37,7 @@
 
 #include <cstdio>
 #include <cstdlib>
-//#include <string.h>
+#include <cstring>
 #include <sys/types.h>
 #include <unistd.h>
 #include <signal.h>
@@ -45,6 +45,7 @@
 #include <iostream>
 #include <fstream>
 #include <memory>
+#include <string>
 
 #include <TSAXParser.h>
 #include <TString.h>
@@ -188,7 +189,7 @@ void musrfit_write_ascii(TString fln, PRunData *data, int runCounter)
  * \param fileName file name
  * \param runList run list collection handler
  */
-void musrfit_dump_ascii(char *fileName, PRunListCollection *runList)
+void musrfit_dump_ascii(const char *fileName, PRunListCollection *runList)
 {
   TString fln(fileName);
   fln.ReplaceAll(".msr", ".dat");
@@ -331,7 +332,7 @@ void musrfit_write_root(TFile &f, TString fln, PRunData *data, int runCounter)
  * \param fileName file name
  * \param runList run list connection handler
  */
-void musrfit_dump_root(char *fileName, PRunListCollection *runList)
+void musrfit_dump_root(const char *fileName, PRunListCollection *runList)
 {
   TString fln(fileName);
   fln.ReplaceAll(".msr", ".root");
@@ -508,7 +509,7 @@ int main(int argc, char *argv[])
 #endif
 
   TString dump("");
-  char filename[1024];
+  std::string filename{};
 
   // add default shared library path /usr/local/lib if not already persent
   const char *dsp = gSystem->GetDynamicPath();
@@ -524,11 +525,9 @@ int main(int argc, char *argv[])
     }
   }
 
-  memset(filename, '\0', sizeof(filename));
-  strcpy(filename, "");
   for (int i=1; i<argc; i++) {
     if (strstr(argv[i], ".msr")) {
-      strncpy(filename, argv[i], sizeof(filename));
+      filename = argv[i];
     } else if (!strcmp(argv[i], "-k") || !strcmp(argv[i], "--keep-mn2-output")) {
       keep_mn2_output = true;
     } else if (!strcmp(argv[i], "-c") || !strcmp(argv[i], "--chisq-only")) {
@@ -622,7 +621,7 @@ int main(int argc, char *argv[])
   }
 
   // check if a filename is present
-  if ((strlen(filename) == 0) && !reset_startup_file) {
+  if (filename.empty() && !reset_startup_file) {
     show_syntax = true;
     std::cout << std::endl << ">> musrfit **ERROR** no msr-file present!" << std::endl;
   }
@@ -643,7 +642,7 @@ int main(int argc, char *argv[])
   }
 
   // read startup file
-  char startup_path_name[128];
+  std::string startup_path_name{};
   std::unique_ptr<TSAXParser> saxParser = std::make_unique<TSAXParser>();
   std::unique_ptr<PStartupHandler> startupHandler = std::make_unique<PStartupHandler>(reset_startup_file);
   if (reset_startup_file) // only rewrite musrfit_startup.xml has been requested
@@ -652,13 +651,12 @@ int main(int argc, char *argv[])
     std::cerr << std::endl << ">> musrfit **WARNING** couldn't find " << startupHandler->GetStartupFilePath().Data();
     std::cerr << std::endl;
   } else {
-    memset(startup_path_name, '\0', sizeof(startup_path_name));
-    strncpy(startup_path_name, startupHandler->GetStartupFilePath().Data(), sizeof(startup_path_name));
+    startup_path_name = startupHandler->GetStartupFilePath().Data();
     saxParser->ConnectToHandler("PStartupHandler", startupHandler.get());
     //status = saxParser->ParseFile(startup_path_name);
     // parsing the file as above seems to lead to problems in certain environments;
     // use the parseXmlFile function instead (see PStartupHandler.cpp for the definition)
-    status = parseXmlFile(saxParser.get(), startup_path_name);
+    status = parseXmlFile(saxParser.get(), startup_path_name.c_str());
     // check for parse errors
     if (status) { // error
       std::cerr << std::endl << ">> musrfit **WARNING** Reading/parsing musrfit_startup.xml failed.";
@@ -674,9 +672,9 @@ int main(int argc, char *argv[])
   // read msr-file
   std::unique_ptr<PMsrHandler> msrHandler;
   if (startupHandler)
-    msrHandler = std::make_unique<PMsrHandler>(filename, &startup_options);
+    msrHandler = std::make_unique<PMsrHandler>(filename.c_str(), &startup_options);
   else
-    msrHandler = std::make_unique<PMsrHandler>(filename);
+    msrHandler = std::make_unique<PMsrHandler>(filename.c_str());
   status = msrHandler->ReadMsrFile();
   if (status != PMUSR_SUCCESS) {
     switch (status) {
@@ -796,9 +794,9 @@ int main(int argc, char *argv[])
     std::cout << std::endl << "will write dump file ..." << std::endl;
     dump.ToLower();
     if (dump.Contains("ascii"))
-      musrfit_dump_ascii(filename, runListCollection.get());
+      musrfit_dump_ascii(filename.c_str(), runListCollection.get());
     else if (dump.Contains("root"))
-      musrfit_dump_root(filename, runListCollection.get());
+      musrfit_dump_root(filename.c_str(), runListCollection.get());
     else
       std::cout << std::endl << "do not know format " << dump.Data() << ", sorry :-| " << std::endl;
   }
@@ -807,16 +805,13 @@ int main(int argc, char *argv[])
   if (success) {
     if (keep_mn2_output && !chisq_only && !fitter->IsScanOnly()) {
       // 1st rename MINUIT2.OUTPUT
-      TString fln = TString(filename);
-      char ext[32];
-      strcpy(ext, "-mn2.output");
-      fln.ReplaceAll(".msr", 4, ext, strlen(ext));
+      TString fln = TString(filename.c_str());
+      fln.ReplaceAll(".msr", "-mn2.output");
       gSystem->CopyFile("MINUIT2.OUTPUT", fln.Data(), kTRUE);
 
       // 2nd rename MINUIT2.ROOT
-      fln = TString(filename);
-      strcpy(ext, "-mn2.root");
-      fln.ReplaceAll(".msr", 4, ext, strlen(ext));
+      fln = TString(filename.c_str());
+      fln.ReplaceAll(".msr", "-mn2.root");
       gSystem->CopyFile("MINUIT2.root", fln.Data(), kTRUE);
     }
   }
@@ -826,13 +821,11 @@ int main(int argc, char *argv[])
       // swap msr- and mlog-file
       std::cout << std::endl << ">> swapping msr-, mlog-file ..." << std::endl;
       // copy msr-file -> __temp.msr
-      gSystem->CopyFile(filename, "__temp.msr", kTRUE);
+      gSystem->CopyFile(filename.c_str(), "__temp.msr", kTRUE);
       // copy mlog-file -> msr-file
-      TString fln = TString(filename);
-      char ext[32];
-      strcpy(ext, ".mlog");
-      fln.ReplaceAll(".msr", 4, ext, strlen(ext));
-      gSystem->CopyFile(fln.Data(), filename, kTRUE);
+      TString fln = TString(filename.c_str());
+      fln.ReplaceAll(".msr", ".mlog");
+      gSystem->CopyFile(fln.Data(), filename.c_str(), kTRUE);
       // copy __temp.msr -> mlog-file
       gSystem->CopyFile("__temp.msr", fln.Data(), kTRUE);
       // delete __temp.msr
diff --git a/src/musrt0.cpp b/src/musrt0.cpp
index f75bb55a..0f6a8909 100644
--- a/src/musrt0.cpp
+++ b/src/musrt0.cpp
@@ -37,6 +37,7 @@
 
 #include <iostream>
 #include <memory>
+#include <string>
 
 #include <TApplication.h>
 #include <TSAXParser.h>
@@ -181,7 +182,7 @@ Int_t main(Int_t argc, Char_t *argv[])
   Bool_t show_syntax = false;
   Int_t  status;
   Bool_t success = true;
-  Char_t filename[1024];
+  std::string filename{};
   Bool_t getT0FromPromptPeak = false;
   Bool_t firstGoodBinOffsetPresent = false;
   Int_t firstGoodBinOffset = 0;
@@ -198,7 +199,6 @@ Int_t main(Int_t argc, Char_t *argv[])
   if (strstr(dsp, "/usr/local/lib") == nullptr)
     gSystem->AddDynamicPath("/usr/local/lib");
 
-  memset(filename, '\0', sizeof(filename));
   for (int i=1; i<argc; i++) {
     if (!strcmp(argv[i], "--version")) {
 #ifdef HAVE_CONFIG_H
@@ -223,8 +223,8 @@ Int_t main(Int_t argc, Char_t *argv[])
       std::cout << std::endl << "  '" << gSystem->GetDynamicPath() << "'" << std::endl << std::endl;
       return PMUSR_SUCCESS;
     } else if (strstr(argv[i], ".msr")) { // check for filename
-      if (strlen(filename) == 0) {
-        strncpy(filename, argv[i], sizeof(filename));
+      if (filename.empty()) {
+        filename = argv[i];
       } else {
         std::cout << std::endl << "**ERROR** only one file name allowed." << std::endl;
         show_syntax = true;
@@ -262,7 +262,7 @@ Int_t main(Int_t argc, Char_t *argv[])
     }
   }
 
-  if (strlen(filename) == 0) {
+  if (filename.empty()) {
     std::cout  << std::endl << "**ERROR** msr-file missing!" << std::endl;
     show_syntax = true;
   }
@@ -273,19 +273,19 @@ Int_t main(Int_t argc, Char_t *argv[])
   }
 
   // read startup file
-  Char_t startup_path_name[128];
+  std::string startup_path_name{};
   std::unique_ptr<TSAXParser> saxParser = std::make_unique<TSAXParser>();
   std::unique_ptr<PStartupHandler> startupHandler = std::make_unique<PStartupHandler>();
   if (!startupHandler->StartupFileFound()) {
     std::cerr << std::endl << ">> musrt0 **WARNING** couldn't find " << startupHandler->GetStartupFilePath().Data();
     std::cerr << std::endl;
   } else {
-    strcpy(startup_path_name, startupHandler->GetStartupFilePath().Data());
+    startup_path_name = startupHandler->GetStartupFilePath().Data();
     saxParser->ConnectToHandler("PStartupHandler", startupHandler.get());
     //status = saxParser->ParseFile(startup_path_name);
     // parsing the file as above seems to lead to problems in certain environments;
     // use the parseXmlFile function instead (see PStartupHandler.cpp for the definition)
-    status = parseXmlFile(saxParser.get(), startup_path_name);
+    status = parseXmlFile(saxParser.get(), startup_path_name.c_str());
     // check for parse errors
     if (status) { // error
       std::cerr << std::endl << ">> musrt0 **WARNING** Reading/parsing musrfit_startup.xml failed.";
@@ -294,7 +294,7 @@ Int_t main(Int_t argc, Char_t *argv[])
   }
 
   // read msr-file
-  std::unique_ptr<PMsrHandler> msrHandler = std::make_unique<PMsrHandler>(filename);
+  std::unique_ptr<PMsrHandler> msrHandler = std::make_unique<PMsrHandler>(filename.c_str());
   status = msrHandler->ReadMsrFile();
   if (status != PMUSR_SUCCESS) {
     switch (status) {
@@ -1165,14 +1165,11 @@ Int_t main(Int_t argc, Char_t *argv[])
 
   // swap msr- and mlog-file
   // copy msr-file -> __temp.msr
-  gSystem->CopyFile(filename, "__temp.msr", kTRUE);
+  gSystem->CopyFile(filename.c_str(), "__temp.msr", kTRUE);
   // copy mlog-file -> msr-file
-  TString fln = TString(filename);
-  Char_t ext[32];
-  memset(ext, '\0', sizeof(ext));
-  strncpy(ext, ".mlog", sizeof(ext));
-  fln.ReplaceAll(".msr", 4, ext, strlen(ext));
-  gSystem->CopyFile(fln.Data(), filename, kTRUE);
+  TString fln = TString(filename.c_str());
+  fln.ReplaceAll(".msr", ".mlog");
+  gSystem->CopyFile(fln.Data(), filename.c_str(), kTRUE);
   // copy __temp.msr -> mlog-file
   gSystem->CopyFile("__temp.msr", fln.Data(), kTRUE);
   // delete __temp.msr
diff --git a/src/musrview.cpp b/src/musrview.cpp
index 18a60151..2f629414 100644
--- a/src/musrview.cpp
+++ b/src/musrview.cpp
@@ -37,6 +37,7 @@
 
 #include <iostream>
 #include <memory>
+#include <string>
 #include <vector>
 #include <sstream>
 
@@ -123,20 +124,17 @@ int main(int argc, char *argv[])
   bool show_syntax{false};
   int  status;
   bool success{true};
-  char fileName[128];
+  std::string fileName{};
   bool fourier{false};
   bool avg{false};
   bool theoAtData{false}; // theory points only at data points
   bool graphicsOutput{false};
   bool asciiOutput{false};
-  char graphicsExtension[128];
+  std::string graphicsExtension{};
   int  timeout{0};
   bool show_errMsgBox{false};
   std::stringstream errMsg;
 
-  memset(fileName, '\0', sizeof(fileName));
-  memset(graphicsExtension, '\0', sizeof(graphicsExtension));
-
   // add default shared library path /usr/local/lib if not already persent
   const char *dsp = gSystem->GetDynamicPath();
   if (strstr(dsp, "/usr/local/lib") == nullptr)
@@ -149,8 +147,8 @@ int main(int argc, char *argv[])
   }
   for (int i=1; i<argc; i++) {
     if (strstr(argv[i], ".msr") || strstr(argv[i], ".mlog")) {
-      if (strlen(fileName) == 0) {
-        strncpy(fileName, argv[i], sizeof(fileName));
+      if (fileName.empty()) {
+        fileName = argv[i];
       } else {
         std::cerr << std::endl << "**ERROR** only one file name allowed." << std::endl;
         show_syntax = true;
@@ -189,7 +187,7 @@ int main(int argc, char *argv[])
                !strcmp(argv[i], "--xpm") || !strcmp(argv[i], "--root")) {
 
       graphicsOutput = true;
-      strncpy(graphicsExtension, argv[i]+2, sizeof(graphicsExtension));
+      graphicsExtension = argv[i]+2;
     } else if (!strcmp(argv[i], "--ascii")) {
       asciiOutput = true;
     } else if (!strcmp(argv[i], "--timeout")) {
@@ -220,20 +218,19 @@ int main(int argc, char *argv[])
   }
 
   // read startup file
-  char startup_path_name[128];
-  memset(startup_path_name, '\0', sizeof(startup_path_name));
+  std::string startup_path_name{};
   std::unique_ptr<TSAXParser> saxParser = std::make_unique<TSAXParser>();
   std::unique_ptr<PStartupHandler> startupHandler = std::make_unique<PStartupHandler>();
   if (!startupHandler->StartupFileFound()) {
     std::cerr << std::endl << ">> musrview **WARNING** couldn't find " << startupHandler->GetStartupFilePath().Data();
     std::cerr << std::endl;
   } else {
-    strncpy(startup_path_name, startupHandler->GetStartupFilePath().Data(), sizeof(startup_path_name));
+    startup_path_name = startupHandler->GetStartupFilePath().Data();
     saxParser->ConnectToHandler("PStartupHandler", startupHandler.get());
     //status = saxParser->ParseFile(startup_path_name);
     // parsing the file as above seems to lead to problems in certain environments;
     // use the parseXmlFile function instead (see PStartupHandler.cpp for the definition)
-    status = parseXmlFile(saxParser.get(), startup_path_name);
+    status = parseXmlFile(saxParser.get(), startup_path_name.c_str());
     // check for parse errors
     if (status) { // error
       std::cerr << std::endl << ">> musrview **WARNING** Reading/parsing musrfit_startup.xml failed.";
@@ -245,7 +242,7 @@ int main(int argc, char *argv[])
   }
 
   // read msr-file
-  std::unique_ptr<PMsrHandler> msrHandler = std::make_unique<PMsrHandler>(fileName);
+  std::unique_ptr<PMsrHandler> msrHandler = std::make_unique<PMsrHandler>(fileName.c_str());
   status = msrHandler->ReadMsrFile();
   if (status != PMUSR_SUCCESS) {
     errMsg << msrHandler->GetLastErrorMsg();
@@ -402,12 +399,12 @@ int main(int argc, char *argv[])
       musrCanvas->Connect("Done(Int_t)", "TApplication", &app, "Terminate(Int_t)");
 
       if (graphicsOutput) {
-        musrCanvas->SaveGraphicsAndQuit(fileName, graphicsExtension);
+        musrCanvas->SaveGraphicsAndQuit(fileName.c_str(), graphicsExtension.c_str());
       }
 
       if (asciiOutput) {
         // generate export data file name
-        TString str(fileName);
+        TString str(fileName.c_str());
         str.Remove(str.Last('.'));
         str += ".dat";
         // save data in batch mode
diff --git a/tests/musrview_check/musrview_check.py b/tests/musrview_check/musrview_check.py
index d09c0d3a..bde71bed 100644
--- a/tests/musrview_check/musrview_check.py
+++ b/tests/musrview_check/musrview_check.py
@@ -21,7 +21,6 @@ import os
 import shutil
 import subprocess
 import sys
-import tempfile
 import time
 
 
@@ -76,36 +75,56 @@ def main():
     msr_basename = os.path.splitext(os.path.basename(args.msr_file))[0]
     ref_subdir = os.path.join(args.ref_dir, args.test_name)
 
-    # ---- run musrview in a temporary directory -------------------------------
+    # ---- run musrview --------------------------------------------------------
+    # musrview always writes its PNGs next to the msr-file, so the test has to
+    # run there and clean up after itself.
     work_dir = os.path.dirname(os.path.abspath(args.msr_file))
-    with tempfile.TemporaryDirectory() as tmp_dir:
-        # snapshot existing PNGs so we only pick up newly created ones
-        pre_existing = set(glob.glob(os.path.join(work_dir, f"{msr_basename}_*.png")))
+    png_glob = os.path.join(work_dir, f"{msr_basename}_*.png")
 
+    # Snapshot the PNGs that are already there together with their mtimes. A PNG
+    # counts as produced by this run if it is either new, or pre-existing but
+    # rewritten (a leftover from an earlier aborted run -- musrview simply
+    # overwrites it). Matching on mtime rather than mere existence keeps stale
+    # leftovers from masking the real output, while still ignoring the PNGs of a
+    # sibling test running concurrently on the same msr-file.
+    pre_existing = {p: os.stat(p).st_mtime_ns for p in glob.glob(png_glob)}
+
+    generated = []
+
+    def collect():
+        """Return the PNGs in work_dir that this musrview run created/rewrote."""
+        found = []
+        for p in glob.glob(png_glob):
+            if pre_existing.get(p) != os.stat(p).st_mtime_ns:
+                found.append(p)
+        return sorted(found)
+
+    def cleanup():
+        """Remove everything this run produced -- must happen on every exit path,
+        otherwise the leftovers pile up in doc/examples."""
+        for png in generated:
+            try:
+                os.remove(png)
+            except OSError:
+                pass
+
+    try:
         cmd = [args.musrview, args.msr_file, "--png"] + musrview_opts
         print(f"running: {' '.join(cmd)}")
-        result = subprocess.run(cmd, capture_output=True, text=True,
-                                cwd=work_dir,
-                                env={**os.environ, "MUSRVIEW_PNG_DIR": tmp_dir})
+        result = subprocess.run(cmd, capture_output=True, text=True, cwd=work_dir)
         if result.returncode != 0:
+            generated = collect()
             print(f"**ERROR** musrview returned exit code {result.returncode}")
             print(result.stdout + result.stderr)
             return 1
 
-        # collect only newly created PNGs (exclude pre-existing ones).
         # musrview has already exited by the time subprocess.run() returns, but on
         # some systems the PNG file's directory entry becomes visible to this
         # process only after a further delay (observed running under ctest, up to
         # several seconds) -- poll for a while instead of failing on the first
         # empty glob.
-        generated = []
         for _ in range(150):
-            generated = sorted(
-                p for p in glob.glob(os.path.join(work_dir, f"{msr_basename}_*.png"))
-                if p not in pre_existing
-            )
-            if not generated:
-                generated = sorted(glob.glob(os.path.join(tmp_dir, f"{msr_basename}_*.png")))
+            generated = collect()
             if generated:
                 break
             time.sleep(0.1)
@@ -123,10 +142,6 @@ def main():
                 dst = os.path.join(ref_subdir, os.path.basename(png))
                 shutil.copy2(png, dst)
                 print(f"  saved reference: {dst}")
-            # clean up generated PNGs from work_dir
-            for png in generated:
-                if os.path.dirname(os.path.abspath(png)) == os.path.abspath(work_dir):
-                    os.remove(png)
             print(f"GENERATE: {len(generated)} reference PNG(s) written to {ref_subdir}")
             return 0
 
@@ -153,11 +168,6 @@ def main():
             else:
                 print(f"PASS: {name}  diff={diff:.6f} <= tol={args.tol:.6f}")
 
-        # clean up generated PNGs from work_dir
-        for png in generated:
-            if os.path.dirname(os.path.abspath(png)) == os.path.abspath(work_dir):
-                os.remove(png)
-
         if compared == 0:
             print("**ERROR** no PNGs were compared")
             return 1
@@ -168,6 +178,8 @@ def main():
 
         print(f"\nAll {compared} PNG(s) PASSED (tol={args.tol})")
         return 0
+    finally:
+        cleanup()
 
 
 if __name__ == "__main__":
diff --git a/tests/musrview_check/ref/musrview-histo-HAL9500/test-histo-HAL9500_0.png b/tests/musrview_check/ref/musrview-histo-HAL9500/test-histo-HAL9500_0.png
index 7b1627be..74d94c8c 100644
Binary files a/tests/musrview_check/ref/musrview-histo-HAL9500/test-histo-HAL9500_0.png and b/tests/musrview_check/ref/musrview-histo-HAL9500/test-histo-HAL9500_0.png differ