diff --git a/src/libs/utils/fileutils.cpp b/src/libs/utils/fileutils.cpp
index 6d75342b994..1479a72d23c 100644
--- a/src/libs/utils/fileutils.cpp
+++ b/src/libs/utils/fileutils.cpp
@@ -721,6 +721,11 @@ FileName &FileName::appendString(QChar str)
     return *this;
 }
 
+QTextStream &operator<<(QTextStream &s, const FileName &fn)
+{
+    return s << fn.toString();
+}
+
 static bool isFileDrop(const QMimeData *d, QList<FileDropSupport::FileSpec> *files = 0)
 {
     // internal drop
diff --git a/src/libs/utils/fileutils.h b/src/libs/utils/fileutils.h
index 4e2403322ba..0a05451fd07 100644
--- a/src/libs/utils/fileutils.h
+++ b/src/libs/utils/fileutils.h
@@ -102,6 +102,7 @@ private:
     FileName(const QString &string);
 };
 
+QTCREATOR_UTILS_EXPORT QTextStream &operator<<(QTextStream &s, const FileName &fn);
 
 class QTCREATOR_UTILS_EXPORT FileUtils {
 public:
diff --git a/src/plugins/clangcodemodel/clangutils.cpp b/src/plugins/clangcodemodel/clangutils.cpp
index f5d3daaa31a..8bf2c8ea043 100644
--- a/src/plugins/clangcodemodel/clangutils.cpp
+++ b/src/plugins/clangcodemodel/clangutils.cpp
@@ -74,17 +74,17 @@ UnsavedFiles createUnsavedFiles(WorkingCopy workingCopy)
     // TODO: change the modelmanager to hold one working copy, and amend it every time we ask for one.
     // TODO: Reason: the UnsavedFile needs a QByteArray.
 
-    QSet<QString> modifiedFiles;
+    QSet<::Utils::FileName> modifiedFiles;
     foreach (IDocument *doc, Core::DocumentManager::modifiedDocuments())
-        modifiedFiles.insert(doc->filePath());
+        modifiedFiles.insert(::Utils::FileName::fromString(doc->filePath()));
 
     UnsavedFiles result;
-    QHashIterator<QString, QPair<QByteArray, unsigned> > wcIter = workingCopy.iterator();
+    QHashIterator<::Utils::FileName, QPair<QByteArray, unsigned> > wcIter = workingCopy.iterator();
     while (wcIter.hasNext()) {
         wcIter.next();
-        const QString &fileName = wcIter.key();
-        if (modifiedFiles.contains(fileName) && QFile(fileName).exists())
-            result.insert(fileName, wcIter.value().first);
+        const ::Utils::FileName &fileName = wcIter.key();
+        if (modifiedFiles.contains(fileName) && QFile(fileName.toString()).exists())
+            result.insert(fileName.toString(), wcIter.value().first);
     }
 
     return result;
diff --git a/src/plugins/cppeditor/cppcodemodelinspectordialog.cpp b/src/plugins/cppeditor/cppcodemodelinspectordialog.cpp
index 9a3811cc2da..7c189f52e29 100644
--- a/src/plugins/cppeditor/cppcodemodelinspectordialog.cpp
+++ b/src/plugins/cppeditor/cppcodemodelinspectordialog.cpp
@@ -1087,10 +1087,11 @@ void WorkingCopyModel::configure(const WorkingCopy &workingCopy)
 {
     emit layoutAboutToBeChanged();
     m_workingCopyList.clear();
-    QHashIterator<QString, QPair<QByteArray, unsigned> > it = workingCopy.iterator();
+    QHashIterator<Utils::FileName, QPair<QByteArray, unsigned> > it = workingCopy.iterator();
     while (it.hasNext()) {
         it.next();
-        m_workingCopyList << WorkingCopyEntry(it.key(), it.value().first, it.value().second);
+        m_workingCopyList << WorkingCopyEntry(it.key().toString(), it.value().first,
+                                              it.value().second);
     }
     emit layoutChanged();
 }
diff --git a/src/plugins/cpptools/cppcodemodelinspectordumper.cpp b/src/plugins/cpptools/cppcodemodelinspectordumper.cpp
index 32c420b2174..e0f44277c43 100644
--- a/src/plugins/cpptools/cppcodemodelinspectordumper.cpp
+++ b/src/plugins/cpptools/cppcodemodelinspectordumper.cpp
@@ -580,10 +580,10 @@ void Dumper::dumpWorkingCopy(const WorkingCopy &workingCopy)
     m_out << "Working Copy contains " << workingCopy.size() << " entries{{{1\n";
 
     const QByteArray i1 = indent(1);
-    QHashIterator<QString, QPair<QByteArray, unsigned> > it = workingCopy.iterator();
+    QHashIterator<::Utils::FileName, QPair<QByteArray, unsigned> > it = workingCopy.iterator();
     while (it.hasNext()) {
         it.next();
-        const QString filePath = it.key();
+        const ::Utils::FileName &filePath = it.key();
         unsigned sourcRevision = it.value().second;
         m_out << i1 << "rev=" << sourcRevision << ", " << filePath << "\n";
     }
diff --git a/src/plugins/cpptools/cppmodelmanager_test.cpp b/src/plugins/cpptools/cppmodelmanager_test.cpp
index 0e7b35f3643..bb0641a7799 100644
--- a/src/plugins/cpptools/cppmodelmanager_test.cpp
+++ b/src/plugins/cpptools/cppmodelmanager_test.cpp
@@ -684,10 +684,10 @@ void CppToolsPlugin::test_modelmanager_extraeditorsupport_uiFiles()
     QCOMPARE(workingCopy.size(), 2); // mm->configurationFileName() and "ui_*.h"
 
     QStringList fileNamesInWorkinCopy;
-    QHashIterator<QString, QPair<QByteArray, unsigned> > it = workingCopy.iterator();
+    QHashIterator<Utils::FileName, QPair<QByteArray, unsigned> > it = workingCopy.iterator();
     while (it.hasNext()) {
         it.next();
-        fileNamesInWorkinCopy << QFileInfo(it.key()).fileName();
+        fileNamesInWorkinCopy << QFileInfo(it.key().toString()).fileName();
     }
     fileNamesInWorkinCopy.sort();
     const QString expectedUiHeaderFileName = _("ui_mainwindow.h");
diff --git a/src/plugins/cpptools/cppworkingcopy.h b/src/plugins/cpptools/cppworkingcopy.h
index 4507c46127c..088fd22a1ec 100644
--- a/src/plugins/cpptools/cppworkingcopy.h
+++ b/src/plugins/cpptools/cppworkingcopy.h
@@ -33,6 +33,8 @@
 
 #include "cpptools_global.h"
 
+#include <utils/fileutils.h>
+
 #include <QHash>
 #include <QString>
 #include <QPair>
@@ -45,28 +47,43 @@ public:
     WorkingCopy();
 
     void insert(const QString &fileName, const QByteArray &source, unsigned revision = 0)
+    { insert(Utils::FileName::fromString(fileName), source, revision); }
+
+    void insert(const Utils::FileName &fileName, const QByteArray &source, unsigned revision = 0)
     { _elements.insert(fileName, qMakePair(source, revision)); }
 
     bool contains(const QString &fileName) const
+    { return contains(Utils::FileName::fromString(fileName)); }
+
+    bool contains(const Utils::FileName &fileName) const
     { return _elements.contains(fileName); }
 
     QByteArray source(const QString &fileName) const
+    { return source(Utils::FileName::fromString(fileName)); }
+
+    QByteArray source(const Utils::FileName &fileName) const
     { return _elements.value(fileName).first; }
 
     unsigned revision(const QString &fileName) const
+    { return revision(Utils::FileName::fromString(fileName)); }
+
+    unsigned revision(const Utils::FileName &fileName) const
     { return _elements.value(fileName).second; }
 
     QPair<QByteArray, unsigned> get(const QString &fileName) const
+    { return get(Utils::FileName::fromString(fileName)); }
+
+    QPair<QByteArray, unsigned> get(const Utils::FileName &fileName) const
     { return _elements.value(fileName); }
 
-    QHashIterator<QString, QPair<QByteArray, unsigned> > iterator() const
-    { return QHashIterator<QString, QPair<QByteArray, unsigned> >(_elements); }
+    QHashIterator<Utils::FileName, QPair<QByteArray, unsigned> > iterator() const
+    { return QHashIterator<Utils::FileName, QPair<QByteArray, unsigned> >(_elements); }
 
     int size() const
     { return _elements.size(); }
 
 private:
-    typedef QHash<QString, QPair<QByteArray, unsigned> > Table;
+    typedef QHash<Utils::FileName, QPair<QByteArray, unsigned> > Table;
     Table _elements;
 };
 
diff --git a/src/plugins/designer/qtcreatorintegration.cpp b/src/plugins/designer/qtcreatorintegration.cpp
index 0abeb9a11f4..75d5aef09ea 100644
--- a/src/plugins/designer/qtcreatorintegration.cpp
+++ b/src/plugins/designer/qtcreatorintegration.cpp
@@ -537,12 +537,14 @@ bool QtCreatorIntegration::navigateToSlot(const QString &objectName,
     } else {
         const CppTools::WorkingCopy workingCopy =
                 CppTools::CppModelManager::instance()->workingCopy();
-        QHashIterator<QString, QPair<QByteArray, unsigned> > it = workingCopy.iterator();
+        const Utils::FileName configFileName =
+                Utils::FileName::fromString(CppTools::CppModelManager::configurationFileName());
+        QHashIterator<Utils::FileName, QPair<QByteArray, unsigned> > it = workingCopy.iterator();
         while (it.hasNext()) {
             it.next();
-            const QString fileName = it.key();
-            if (fileName != CppTools::CppModelManager::configurationFileName())
-                newDocTable.insert(docTable.document(fileName));
+            const Utils::FileName &fileName = it.key();
+            if (fileName != configFileName)
+                newDocTable.insert(docTable.document(fileName.toString()));
         }
     }
     docTable = newDocTable;