diff --git a/app/actions.cpp b/app/actions.cpp
index a43f163a..5e933af7 100644
--- a/app/actions.cpp
+++ b/app/actions.cpp
@@ -926,7 +926,7 @@ int Extract::writeIccProfile(const std::string& target) const {
 }  // Extract::writeIccProfile
 
 void Extract::writePreviewFile(const Exiv2::PreviewImage& pvImg, size_t num) const {
-  std::string pvFile = newFilePath(path_, "-preview") + Exiv2::toString(num);
+  std::string pvFile = newFilePath(path_, "-preview") + std::to_string(num);
   std::string pvPath = pvFile + pvImg.extension();
   if (dontOverwrite(pvPath))
     return;
diff --git a/app/exiv2.cpp b/app/exiv2.cpp
index f9675b07..863ee61f 100644
--- a/app/exiv2.cpp
+++ b/app/exiv2.cpp
@@ -1323,14 +1323,14 @@ bool parseLine(ModifyCmd& modifyCmd, const std::string& line, int num) {
     }
 #endif
     throw Exiv2::Error(Exiv2::ErrorCode::kerErrorMessage,
-                       Exiv2::toString(num) + ": " + _("Invalid command line:") + cmdLine);
+                       std::to_string(num) + ": " + _("Invalid command line:") + cmdLine);
   }
 
   std::string cmd(line.substr(cmdStart, cmdEnd - cmdStart));
   CmdId cmdId = commandId(cmd);
   if (cmdId == CmdId::invalid) {
     throw Exiv2::Error(Exiv2::ErrorCode::kerErrorMessage,
-                       Exiv2::toString(num) + ": " + _("Invalid command") + " `" + cmd + "'");
+                       std::to_string(num) + ": " + _("Invalid command") + " `" + cmd + "'");
   }
 
   Exiv2::TypeId defaultType = Exiv2::invalidTypeId;
@@ -1361,7 +1361,7 @@ bool parseLine(ModifyCmd& modifyCmd, const std::string& line, int num) {
     }
     if (metadataId == MetadataId::invalid) {
       throw Exiv2::Error(Exiv2::ErrorCode::kerErrorMessage,
-                         Exiv2::toString(num) + ": " + _("Invalid key") + " `" + key + "'");
+                         std::to_string(num) + ": " + _("Invalid key") + " `" + key + "'");
     }
   }
   std::string value;
@@ -1382,7 +1382,7 @@ bool parseLine(ModifyCmd& modifyCmd, const std::string& line, int num) {
 
     if (cmdId == CmdId::reg && (keyEnd == std::string::npos || valStart == std::string::npos)) {
       throw Exiv2::Error(Exiv2::ErrorCode::kerErrorMessage,
-                         Exiv2::toString(num) + ": " + _("Invalid command line") + " ");
+                         std::to_string(num) + ": " + _("Invalid command line") + " ");
     }
 
     if (cmdId != CmdId::reg && typeStart != std::string::npos && typeEnd != std::string::npos) {
@@ -1392,7 +1392,7 @@ bool parseLine(ModifyCmd& modifyCmd, const std::string& line, int num) {
         valStart = line.find_first_not_of(delim, typeEnd + 1);
         if (valStart == std::string::npos) {
           throw Exiv2::Error(Exiv2::ErrorCode::kerErrorMessage,
-                             Exiv2::toString(num) + ": " + _("Invalid command line") + " ");
+                             std::to_string(num) + ": " + _("Invalid command line") + " ");
         }
         type = tmpType;
         explicitType = true;
@@ -1418,7 +1418,7 @@ bool parseLine(ModifyCmd& modifyCmd, const std::string& line, int num) {
   if (cmdId == CmdId::reg) {
     if (value.empty()) {
       throw Exiv2::Error(Exiv2::ErrorCode::kerErrorMessage,
-                         Exiv2::toString(num) + ": " + _("Empty value for key") + +" `" + key + "'");
+                         std::to_string(num) + ": " + _("Empty value for key") + +" `" + key + "'");
     }
 
     // Registration needs to be done immediately as the new namespaces are
diff --git a/samples/prevtest.cpp b/samples/prevtest.cpp
index 4ef44141..d843a13a 100644
--- a/samples/prevtest.cpp
+++ b/samples/prevtest.cpp
@@ -29,7 +29,7 @@ int main(int argc, char* const argv[]) try {
               << "\n";
 
     Exiv2::PreviewImage preview = loader.getPreviewImage(pos);
-    auto s = preview.writeFile(filename + "_" + Exiv2::toString(pos.width_) + "x" + Exiv2::toString(pos.height_));
+    auto s = preview.writeFile(filename + "_" + std::to_string(pos.width_) + "x" + std::to_string(pos.height_));
     if (s == 0)
       return EXIT_FAILURE;
   }
diff --git a/src/convert.cpp b/src/convert.cpp
index 9195e662..4c1c34cc 100644
--- a/src/convert.cpp
+++ b/src/convert.cpp
@@ -947,7 +947,7 @@ void Converter::cnvXmpDate(const char* from, const char* to) {
         }
         if (subsecTag) {
           prepareExifTarget(subsecTag, true);
-          (*exifData_)[subsecTag] = toString(datetime.nanoSecond);
+          (*exifData_)[subsecTag] = std::to_string(datetime.nanoSecond);
         }
       }
     } else {  // "Exif.GPSInfo.GPSTimeStamp"
diff --git a/src/error.cpp b/src/error.cpp
index 4a53e751..f2e212c5 100644
--- a/src/error.cpp
+++ b/src/error.cpp
@@ -165,7 +165,7 @@ void Error::setMsg(int count) {
   std::string msg{errList.at(static_cast<size_t>(code_))};
   auto pos = msg.find("%0");
   if (pos != std::string::npos) {
-    msg.replace(pos, 2, toString(static_cast<int>(code_)));
+    msg.replace(pos, 2, std::to_string(static_cast<int>(code_)));
   }
   if (count > 0) {
     pos = msg.find("%1");
diff --git a/src/nikonmn_int.cpp b/src/nikonmn_int.cpp
index 83e48aea..fd5e7206 100644
--- a/src/nikonmn_int.cpp
+++ b/src/nikonmn_int.cpp
@@ -3328,7 +3328,7 @@ std::ostream& Nikon3MakerNote::print0x009e(std::ostream& os, const Value& value,
     if (td) {
       s = std::string(exvGettext(td->label_)).append(d).append(s);
     } else {
-      s = std::string(_("Unknown")).append(" (").append(toString(l)).append(")").append(d).append(s);
+      s = std::string(_("Unknown")).append(" (").append(std::to_string(l)).append(")").append(d).append(s);
     }
   }
   return os << s;
diff --git a/src/preview.cpp b/src/preview.cpp
index 731a8186..87848ffe 100644
--- a/src/preview.cpp
+++ b/src/preview.cpp
@@ -954,7 +954,7 @@ DataBuf makePnm(size_t width, size_t height, const DataBuf& rgb) {
     return {};
   }
 
-  const std::string header = "P6\n" + toString(width) + " " + toString(height) + "\n255\n";
+  const std::string header = "P6\n" + std::to_string(width) + " " + std::to_string(height) + "\n255\n";
   const auto headerBytes = reinterpret_cast<const byte*>(header.data());
 
   DataBuf dest(header.size() + rgb.size());