diff --git a/Source/cmExportCMakeConfigGenerator.cxx b/Source/cmExportCMakeConfigGenerator.cxx
index 83bf0e8fb5..7228d206ca 100644
--- a/Source/cmExportCMakeConfigGenerator.cxx
+++ b/Source/cmExportCMakeConfigGenerator.cxx
@@ -127,13 +127,14 @@ void cmExportCMakeConfigGenerator::SetImportLinkInterface(
 
   if (!this->ExportOld) {
     cmLocalGenerator* lg = target->GetLocalGenerator();
-    std::ostringstream e;
-    e << "Target \"" << target->GetName()
-      << "\" has policy CMP0022 enabled, "
-         "but also has old-style LINK_INTERFACE_LIBRARIES properties "
-         "populated, but it was exported without the "
-         "EXPORT_LINK_INTERFACE_LIBRARIES to export the old-style properties";
-    lg->IssueMessage(MessageType::FATAL_ERROR, e.str());
+    lg->IssueMessage(
+      MessageType::FATAL_ERROR,
+      cmStrCat(
+        "Target \"", target->GetName(),
+        "\" has policy CMP0022 enabled, "
+        "but also has old-style LINK_INTERFACE_LIBRARIES properties "
+        "populated, but it was exported without the "
+        "EXPORT_LINK_INTERFACE_LIBRARIES to export the old-style properties"));
     return;
   }
 
diff --git a/Source/cmExportCommand.cxx b/Source/cmExportCommand.cxx
index e2dd9a6865..c570b7784f 100644
--- a/Source/cmExportCommand.cxx
+++ b/Source/cmExportCommand.cxx
@@ -3,7 +3,6 @@
 #include "cmExportCommand.h"
 
 #include <map>
-#include <sstream>
 #include <utility>
 
 #include <cm/memory>
@@ -152,10 +151,9 @@ static bool HandleTargetsMode(std::vector<std::string> const& args,
   } else {
     // Make sure the file has a .cmake extension.
     if (!cmHasSuffix(arguments.Filename, ".cmake"_s)) {
-      std::ostringstream e;
-      e << "FILE option given filename \"" << arguments.Filename
-        << "\" which does not have an extension of \".cmake\".\n";
-      status.SetError(e.str());
+      status.SetError(
+        cmStrCat("FILE option given filename \"", arguments.Filename,
+                 "\" which does not have an extension of \".cmake\".\n"));
       return false;
     }
     fname = arguments.Filename;
@@ -166,10 +164,8 @@ static bool HandleTargetsMode(std::vector<std::string> const& args,
   // Get the file to write.
   if (cmSystemTools::FileIsFullPath(fname)) {
     if (!mf.CanIWriteThisFile(fname)) {
-      std::ostringstream e;
-      e << "FILE option given filename \"" << fname
-        << "\" which is in the source tree.\n";
-      status.SetError(e.str());
+      status.SetError(cmStrCat("FILE option given filename \"", fname,
+                               "\" which is in the source tree.\n"));
       return false;
     }
   } else {
@@ -297,10 +293,9 @@ static bool HandleExportMode(std::vector<std::string> const& args,
     fname = arguments.ExportSetName + ".cmake";
   } else {
     if (!cmHasSuffix(arguments.Filename, ".cmake"_s)) {
-      std::ostringstream e;
-      e << "FILE option given filename \"" << arguments.Filename
-        << "\" which does not have an extension of \".cmake\".\n";
-      status.SetError(e.str());
+      status.SetError(
+        cmStrCat("FILE option given filename \"", arguments.Filename,
+                 "\" which does not have an extension of \".cmake\".\n"));
       return false;
     }
     fname = arguments.Filename;
@@ -308,10 +303,8 @@ static bool HandleExportMode(std::vector<std::string> const& args,
 
   if (cmSystemTools::FileIsFullPath(fname)) {
     if (!mf.CanIWriteThisFile(fname)) {
-      std::ostringstream e;
-      e << "FILE option given filename \"" << fname
-        << "\" which is in the source tree.\n";
-      status.SetError(e.str());
+      status.SetError(cmStrCat("FILE option given filename \"", fname,
+                               "\" which is in the source tree.\n"));
       return false;
     }
   } else {
@@ -607,9 +600,7 @@ static bool HandlePackageMode(std::vector<std::string> const& args,
       package = args[i];
       doing = DoingNone;
     } else {
-      std::ostringstream e;
-      e << "PACKAGE given unknown argument: " << args[i];
-      status.SetError(e.str());
+      status.SetError("PACKAGE given unknown argument: " + args[i]);
       return false;
     }
   }
@@ -622,10 +613,9 @@ static bool HandlePackageMode(std::vector<std::string> const& args,
   char const* packageExpr = "^[A-Za-z0-9_.-]+$";
   cmsys::RegularExpression packageRegex(packageExpr);
   if (!packageRegex.find(package)) {
-    std::ostringstream e;
-    e << "PACKAGE given invalid package name \"" << package << "\".  "
-      << "Package names must match \"" << packageExpr << "\".";
-    status.SetError(e.str());
+    status.SetError(cmStrCat("PACKAGE given invalid package name \"", package,
+                             "\".  Package names must match \"", packageExpr,
+                             "\"."));
     return false;
   }
 
@@ -665,17 +655,15 @@ static bool HandlePackageMode(std::vector<std::string> const& args,
 static void ReportRegistryError(cmMakefile& mf, std::string const& msg,
                                 std::string const& key, long err)
 {
-  std::ostringstream e;
-  e << msg << "\n"
-    << "  HKEY_CURRENT_USER\\" << key << "\n";
+  std::string e = cmStrCat(msg, "\n  HKEY_CURRENT_USER\\", key, '\n');
   wchar_t winmsg[1024];
   if (FormatMessageW(
         FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, 0, err,
         MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), winmsg, 1024, 0) > 0) {
-    e << "Windows reported:\n"
-      << "  " << cmsys::Encoding::ToNarrow(winmsg);
+    e = cmStrCat(std::move(e), "Windows reported:\n  ",
+                 cmsys::Encoding::ToNarrow(winmsg));
   }
-  mf.IssueMessage(MessageType::WARNING, e.str());
+  mf.IssueMessage(MessageType::WARNING, e);
 }
 
 static void StorePackageRegistry(cmMakefile& mf, std::string const& package,
@@ -698,9 +686,9 @@ static void StorePackageRegistry(cmMakefile& mf, std::string const& package,
                    static_cast<DWORD>(wcontent.size() + 1) * sizeof(wchar_t));
   RegCloseKey(hKey);
   if (err != ERROR_SUCCESS) {
-    std::ostringstream msg;
-    msg << "Cannot set registry value \"" << hash << "\" under key";
-    ReportRegistryError(mf, msg.str(), key, err);
+    ReportRegistryError(
+      mf, cmStrCat("Cannot set registry value \"", hash, "\" under key"), key,
+      err);
     return;
   }
 }
diff --git a/Source/cmakemain.cxx b/Source/cmakemain.cxx
index 6d9c74e15e..c3b3b1531f 100644
--- a/Source/cmakemain.cxx
+++ b/Source/cmakemain.cxx
@@ -10,7 +10,6 @@
 #include <cstring>
 #include <functional>
 #include <iostream>
-#include <sstream>
 #include <string>
 #include <utility>
 #include <vector>
@@ -846,15 +845,7 @@ bool parse_default_directory_permissions(std::string const& permissions,
     return false;
   }
 
-  std::ostringstream oss;
-  for (auto i = 0u; i < parsedPermissions.size(); i++) {
-    if (i != 0) {
-      oss << ';';
-    }
-    oss << parsedPermissions[i];
-  }
-
-  parsedPermissionsVar = oss.str();
+  parsedPermissionsVar = cmJoin(parsedPermissions, ";");
   return true;
 }