4 files changed, 15 insertions, 2 deletions
diff --git a/qmake/generators/win32/mingw_make.cpp b/qmake/generators/win32/mingw_make.cpp
index 97bfef88a4..1837c6c0cf 100644
--- a/qmake/generators/win32/mingw_make.cpp
+++ b/qmake/generators/win32/mingw_make.cpp
@@ -112,6 +112,18 @@ bool MingwMakefileGenerator::writeMakefile(QTextStream &t)
     return false;
  }
 
+QString MingwMakefileGenerator::installRoot() const
+{
+    /*
+      We include a magic prefix on the path to bypass mingw-make's "helpful"
+      intervention in the environment, recognising variables that look like
+      paths and adding the msys system root as prefix, which we don't want.
+      Once this hack has smuggled INSTALL_ROOT into make's variable space, we
+      can trivially strip the magic prefix back off to get the path we meant.
+     */
+    return QStringLiteral("$(INSTALL_ROOT:@msyshack@%=%)");
+}
+
 void createLdObjectScriptFile(const QString &fileName, const ProStringList &objList)
 {
     QString filePath = Option::output_dir + QDir::separator() + fileName;
diff --git a/qmake/generators/win32/mingw_make.h b/qmake/generators/win32/mingw_make.h
index 4e94a23ae2..1525f04955 100644
--- a/qmake/generators/win32/mingw_make.h
+++ b/qmake/generators/win32/mingw_make.h
@@ -50,6 +50,7 @@ protected:
     virtual QString getManifestFileForRcFile() const;
     bool writeMakefile(QTextStream &);
     void init();
+    virtual QString installRoot() const;
 private:
     void writeMingwParts(QTextStream &);
     void writeIncPart(QTextStream &t);
diff --git a/qmake/generators/win32/msvc_nmake.cpp b/qmake/generators/win32/msvc_nmake.cpp
index 7499d76e75..27427db68b 100644
--- a/qmake/generators/win32/msvc_nmake.cpp
+++ b/qmake/generators/win32/msvc_nmake.cpp
@@ -268,7 +268,7 @@ QString NmakeMakefileGenerator::defaultInstall(const QString &t)
 
     QString ret = Win32MakefileGenerator::defaultInstall(t);
 
-    const QString root = "$(INSTALL_ROOT)";
+    const QString root = installRoot();
     ProStringList &uninst = project->values(ProKey(t + ".uninstall"));
     QString targetdir = fileFixify(project->first(ProKey(t + ".path")).toQString(), FileFixifyAbsolute);
     if(targetdir.right(1) != Option::dir_sep)
diff --git a/qmake/generators/win32/winmakefile.cpp b/qmake/generators/win32/winmakefile.cpp
index 1fba7057ab..a042cb0d4b 100644
--- a/qmake/generators/win32/winmakefile.cpp
+++ b/qmake/generators/win32/winmakefile.cpp
@@ -689,7 +689,7 @@ QString Win32MakefileGenerator::defaultInstall(const QString &t)
         project->first("TEMPLATE") == "subdirs" || project->first("TEMPLATE") == "aux")
        return QString();
 
-    const QString root = "$(INSTALL_ROOT)";
+    const QString root = installRoot();
     ProStringList &uninst = project->values(ProKey(t + ".uninstall"));
     QString ret;
     QString targetdir = fileFixify(project->first(ProKey(t + ".path")).toQString(), FileFixifyAbsolute);