diff --git a/qmake/generators/makefile.cpp b/qmake/generators/makefile.cpp
index 12004c62c36..762ae66a1ab 100644
--- a/qmake/generators/makefile.cpp
+++ b/qmake/generators/makefile.cpp
@@ -318,8 +318,8 @@ MakefileGenerator::findFilesInVPATH(ProStringList l, uchar flags, const QString
                                                 QDir::NoDotAndDotDot | QDir::AllEntries);
                     if(files.isEmpty()) {
                         debug_msg(1, "%s:%d Failure to find %s in vpath (%s)",
-                                  __FILE__, __LINE__,
-                                  val.toLatin1().constData(), vpath.join("::").toLatin1().constData());
+                                  __FILE__, __LINE__, val.toLatin1().constData(),
+                                  vpath.join(QString("::")).toLatin1().constData());
                         if(flags & VPATH_RemoveMissingFiles)
                             remove_file = true;
                         else if(flags & VPATH_WarnMissingFiles)
@@ -780,7 +780,8 @@ MakefileGenerator::init()
         for (ProStringList::Iterator it = incDirs.begin(); it != incDirs.end(); ++it)
             deplist.append(QMakeLocalFileName((*it).toQString()));
         QMakeSourceFileInfo::setDependencyPaths(deplist);
-        debug_msg(1, "Dependency Directories: %s", incDirs.join(" :: ").toLatin1().constData());
+        debug_msg(1, "Dependency Directories: %s",
+                  incDirs.join(QString(" :: ")).toLatin1().constData());
         //cache info
         if(project->isActiveConfig("qmake_cache")) {
             QString cache_file;
@@ -2183,7 +2184,7 @@ MakefileGenerator::writeExtraVariables(QTextStream &t)
     }
     if (!outlist.isEmpty()) {
         t << "####### Custom Variables\n";
-        t << outlist.join("\n") << endl << endl;
+        t << outlist.join('\n') << endl << endl;
     }
 }
 
@@ -2727,7 +2728,7 @@ MakefileGenerator::writeMakeQmake(QTextStream &t, bool noDummyQmakeAll)
                     t << escapeDependencyPath(specdir() + Option::dir_sep + "qmake.conf") << " ";
             }
             const ProStringList &included = escapeDependencyPaths(project->values("QMAKE_INTERNAL_INCLUDED_FILES"));
-            t << included.join(" \\\n\t\t") << "\n\t"
+            t << included.join(QString(" \\\n\t\t")) << "\n\t"
               << qmake << endl;
             for(int include = 0; include < included.size(); ++include) {
                 const ProString &i = included.at(include);
diff --git a/qmake/generators/unix/unixmake2.cpp b/qmake/generators/unix/unixmake2.cpp
index 9312f19418a..c53393e2681 100644
--- a/qmake/generators/unix/unixmake2.cpp
+++ b/qmake/generators/unix/unixmake2.cpp
@@ -241,13 +241,14 @@ UnixMakefileGenerator::writeMakeParts(QTextStream &t)
                 t << "\\\n\t\t" << (*objit);
         }
         if(incrs_out.count() == objs.count()) { //we just switched places, no real incrementals to be done!
-            t << escapeFilePaths(incrs_out).join(" \\\n\t\t") << endl;
+            t << escapeFilePaths(incrs_out).join(QString(" \\\n\t\t")) << endl;
         } else if(!incrs_out.count()) {
             t << endl;
         } else {
             src_incremental = true;
             t << endl;
-            t << "INCREMENTAL_OBJECTS = " << escapeFilePaths(incrs_out).join(" \\\n\t\t") << endl;
+            t << "INCREMENTAL_OBJECTS = "
+              << escapeFilePaths(incrs_out).join(QString(" \\\n\t\t")) << endl;
         }
     } else {
         // Used all over the place in both deps and commands.
diff --git a/qmake/generators/win32/msvc_vcproj.cpp b/qmake/generators/win32/msvc_vcproj.cpp
index 91054860963..51cf5abdd4f 100644
--- a/qmake/generators/win32/msvc_vcproj.cpp
+++ b/qmake/generators/win32/msvc_vcproj.cpp
@@ -490,7 +490,8 @@ ProStringList VcprojGenerator::collectDependencies(QMakeProject *proj, QHash<QSt
                 // Check if all requirements are fulfilled
                 if (!tmp_proj.isEmpty("QMAKE_FAILED_REQUIREMENTS")) {
                     fprintf(stderr, "Project file(%s) not added to Solution because all requirements not met:\n\t%s\n",
-                        fn.toLatin1().constData(), tmp_proj.values("QMAKE_FAILED_REQUIREMENTS").join(" ").toLatin1().constData());
+                            fn.toLatin1().constData(),
+                            tmp_proj.values("QMAKE_FAILED_REQUIREMENTS").join(' ').toLatin1().constData());
                     qmake_setpwd(oldpwd);
                     Option::output_dir = oldoutpwd;
                     continue;
diff --git a/qmake/library/proitems.cpp b/qmake/library/proitems.cpp
index 5f923744be1..dc84c40d063 100644
--- a/qmake/library/proitems.cpp
+++ b/qmake/library/proitems.cpp
@@ -365,6 +365,11 @@ static QString ProStringList_join(const ProStringList &this_, const QChar *sep,
     return res;
 }
 
+QString ProStringList::join(const ProString &sep) const
+{
+    return ProStringList_join(*this, sep.constData(), sep.size());
+}
+
 QString ProStringList::join(const QString &sep) const
 {
     return ProStringList_join(*this, sep.constData(), sep.size());
diff --git a/qmake/library/proitems.h b/qmake/library/proitems.h
index dcff970600a..f373f928df3 100644
--- a/qmake/library/proitems.h
+++ b/qmake/library/proitems.h
@@ -233,6 +233,7 @@ public:
 
     int length() const { return size(); }
 
+    QString join(const ProString &sep) const;
     QString join(const QString &sep) const;
     QString join(QChar sep) const;
 
diff --git a/qmake/library/qmakebuiltins.cpp b/qmake/library/qmakebuiltins.cpp
index 80569e503af..d927b409b14 100644
--- a/qmake/library/qmakebuiltins.cpp
+++ b/qmake/library/qmakebuiltins.cpp
@@ -596,10 +596,9 @@ ProStringList QMakeEvaluator::evaluateBuiltinExpand(
         if (args.count() < 1 || args.count() > 4) {
             evalError(fL1S("join(var, glue, before, after) requires one to four arguments."));
         } else {
-            QString glue;
-            ProString before, after;
+            ProString glue, before, after;
             if (args.count() >= 2)
-                glue = args.at(1).toQString(m_tmp1);
+                glue = args.at(1);
             if (args.count() >= 3)
                 before = args[2];
             if (args.count() == 4)