diff --git a/src/plugins/madde/maemotoolchain.cpp b/src/plugins/madde/maemotoolchain.cpp
index 549a54e0622..52558fd08aa 100644
--- a/src/plugins/madde/maemotoolchain.cpp
+++ b/src/plugins/madde/maemotoolchain.cpp
@@ -61,9 +61,7 @@ static const char *const MAEMO_QT_VERSION_KEY = "Qt4ProjectManager.Maemo.QtVersi
 MaemoToolChain::MaemoToolChain(bool autodetected) :
     ProjectExplorer::GccToolChain(QLatin1String(Constants::MAEMO_TOOLCHAIN_ID), autodetected),
     m_qtVersionId(-1)
-{
-    updateId();
-}
+{ }
 
 MaemoToolChain::MaemoToolChain(const MaemoToolChain &tc) :
     ProjectExplorer::GccToolChain(tc),
@@ -78,11 +76,6 @@ QString MaemoToolChain::typeName() const
     return MaemoToolChainFactory::tr("Maemo GCC");
 }
 
-ProjectExplorer::Abi MaemoToolChain::targetAbi() const
-{
-    return m_targetAbi;
-}
-
 Utils::FileName MaemoToolChain::mkspec() const
 {
     return Utils::FileName(); // always use default
@@ -90,7 +83,7 @@ Utils::FileName MaemoToolChain::mkspec() const
 
 bool MaemoToolChain::isValid() const
 {
-    return GccToolChain::isValid() && m_qtVersionId >= 0 && m_targetAbi.isValid();
+    return GccToolChain::isValid() && m_qtVersionId >= 0 && targetAbi().isValid();
 }
 
 bool MaemoToolChain::canClone() const
@@ -144,9 +137,9 @@ bool MaemoToolChain::fromMap(const QVariantMap &data)
 void MaemoToolChain::setQtVersionId(int id)
 {
     if (id < 0) {
-        m_targetAbi = ProjectExplorer::Abi();
+        setTargetAbi(ProjectExplorer::Abi());
         m_qtVersionId = -1;
-        updateId(); // Will trigger toolChainUpdated()!
+        toolChainUpdated();
         return;
     }
 
@@ -157,9 +150,10 @@ void MaemoToolChain::setQtVersionId(int id)
     Q_ASSERT(version->qtAbis().count() == 1);
 
     m_qtVersionId = id;
-    m_targetAbi = version->qtAbis().at(0);
+    setTargetAbi(version->qtAbis().at(0));
+
+    toolChainUpdated();
 
-    updateId(); // Will trigger toolChainUpdated()!
     setDisplayName(MaemoToolChainFactory::tr("Maemo GCC for %1").arg(version->displayName()));
 }
 
@@ -168,10 +162,11 @@ int MaemoToolChain::qtVersionId() const
     return m_qtVersionId;
 }
 
-void MaemoToolChain::updateId()
+QString MaemoToolChain::legacyId() const
 {
-    setId(QString::fromLatin1("%1:%2.%3").arg(Constants::MAEMO_TOOLCHAIN_ID)
-          .arg(m_qtVersionId).arg(debuggerCommand().toString()));
+    return QString::fromLatin1("%1:%2.%3").arg(Constants::MAEMO_TOOLCHAIN_ID)
+                                          .arg(m_qtVersionId)
+                                          .arg(debuggerCommand().toString());
 }
 
 // --------------------------------------------------------------------------
@@ -241,6 +236,21 @@ QList<ProjectExplorer::ToolChain *> MaemoToolChainFactory::autoDetect()
     return createToolChainList(versionList);
 }
 
+bool MaemoToolChainFactory::canRestore(const QVariantMap &data)
+{
+    return idFromMap(data).startsWith(QLatin1String(Constants::MAEMO_TOOLCHAIN_ID) + QLatin1Char(':'));
+}
+
+ProjectExplorer::ToolChain *MaemoToolChainFactory::restore(const QVariantMap &data)
+{
+    MaemoToolChain *tc = new MaemoToolChain(false);
+    if (tc->fromMap(data))
+        return tc;
+
+    delete tc;
+    return 0;
+}
+
 void MaemoToolChainFactory::handleQtVersionChanges(const QList<int> &changes)
 {
     ProjectExplorer::ToolChainManager *tcm = ProjectExplorer::ToolChainManager::instance();
diff --git a/src/plugins/madde/maemotoolchain.h b/src/plugins/madde/maemotoolchain.h
index 86bad1f4a44..2fab199e279 100644
--- a/src/plugins/madde/maemotoolchain.h
+++ b/src/plugins/madde/maemotoolchain.h
@@ -49,7 +49,6 @@ public:
     ~MaemoToolChain();
 
     QString typeName() const;
-    ProjectExplorer::Abi targetAbi() const;
     Utils::FileName mkspec() const;
 
     bool isValid() const;
@@ -67,15 +66,14 @@ public:
     void setQtVersionId(int);
     int qtVersionId() const;
 
-private:
-    void updateId();
+    QString legacyId() const;
 
+private:
     explicit MaemoToolChain(bool);
     MaemoToolChain(const MaemoToolChain &);
 
     int m_qtVersionId;
     mutable QString m_sysroot;
-    ProjectExplorer::Abi m_targetAbi;
 
     friend class MaemoToolChainFactory;
 };
@@ -112,6 +110,9 @@ public:
 
     QList<ProjectExplorer::ToolChain *> autoDetect();
 
+    bool canRestore(const QVariantMap &data);
+    ProjectExplorer::ToolChain *restore(const QVariantMap &data);
+
 private slots:
     void handleQtVersionChanges(const QList<int> &);
     QList<ProjectExplorer::ToolChain *> createToolChainList(const QList<int> &);
diff --git a/src/plugins/projectexplorer/abstractmsvctoolchain.cpp b/src/plugins/projectexplorer/abstractmsvctoolchain.cpp
index ddf7725d930..988c61d97cd 100644
--- a/src/plugins/projectexplorer/abstractmsvctoolchain.cpp
+++ b/src/plugins/projectexplorer/abstractmsvctoolchain.cpp
@@ -132,7 +132,6 @@ void AbstractMsvcToolChain::setDebuggerCommand(const Utils::FileName &d)
     if (m_debuggerCommand == d)
         return;
     m_debuggerCommand = d;
-    updateId();
     toolChainUpdated();
 }
 
diff --git a/src/plugins/projectexplorer/abstractmsvctoolchain.h b/src/plugins/projectexplorer/abstractmsvctoolchain.h
index c04db96dfa4..b57b1641ce0 100644
--- a/src/plugins/projectexplorer/abstractmsvctoolchain.h
+++ b/src/plugins/projectexplorer/abstractmsvctoolchain.h
@@ -68,7 +68,6 @@ public:
 protected:
     virtual Utils::Environment readEnvironmentSetting(Utils::Environment& env) const = 0;
     virtual QByteArray msvcPredefinedMacros(const Utils::Environment& env) const;
-    virtual void updateId() = 0;
 
     bool generateEnvironmentSettings(Utils::Environment &env,
                                      const QString& batchFile,
diff --git a/src/plugins/projectexplorer/buildconfiguration.cpp b/src/plugins/projectexplorer/buildconfiguration.cpp
index ea4b561fce9..197a294bdd4 100644
--- a/src/plugins/projectexplorer/buildconfiguration.cpp
+++ b/src/plugins/projectexplorer/buildconfiguration.cpp
@@ -43,6 +43,7 @@
 
 #include <coreplugin/variablemanager.h>
 
+#include <utils/qtcassert.h>
 #include <utils/stringutils.h>
 
 #include <QtCore/QProcess>
@@ -194,12 +195,13 @@ bool BuildConfiguration::fromMap(const QVariantMap &map)
         m_stepLists.append(list);
     }
 
-    QString id = map.value(QLatin1String(TOOLCHAIN_KEY)).toString();
-    m_toolChain = ToolChainManager::instance()->findToolChain(id);
+    const QString id = map.value(QLatin1String(TOOLCHAIN_KEY)).toString();
+    setToolChain(ToolChainManager::instance()->findToolChain(id)); // Do not validate the tool chain as
+                                                                   // the BC is not completely set up yet!
 
     // TODO: We currently assume there to be at least a clean and build list!
-    Q_ASSERT(knownStepLists().contains(QLatin1String(ProjectExplorer::Constants::BUILDSTEPS_BUILD)));
-    Q_ASSERT(knownStepLists().contains(QLatin1String(ProjectExplorer::Constants::BUILDSTEPS_CLEAN)));
+    QTC_CHECK(knownStepLists().contains(QLatin1String(ProjectExplorer::Constants::BUILDSTEPS_BUILD)));
+    QTC_CHECK(knownStepLists().contains(QLatin1String(ProjectExplorer::Constants::BUILDSTEPS_CLEAN)));
 
     return ProjectConfiguration::fromMap(map);
 }
diff --git a/src/plugins/projectexplorer/gcctoolchain.cpp b/src/plugins/projectexplorer/gcctoolchain.cpp
index 87cf476ea5d..6b46538495a 100644
--- a/src/plugins/projectexplorer/gcctoolchain.cpp
+++ b/src/plugins/projectexplorer/gcctoolchain.cpp
@@ -308,13 +308,13 @@ QString GccToolChain::defaultDisplayName() const
                                                  ProjectExplorer::Abi::toString(m_targetAbi.wordWidth()));
 }
 
-void GccToolChain::updateId()
+QString GccToolChain::legacyId() const
 {
     QString i = id();
     i = i.left(i.indexOf(QLatin1Char(':')));
-    setId(QString::fromLatin1("%1:%2.%3.%4")
-          .arg(i).arg(m_compilerPath)
-          .arg(m_targetAbi.toString()).arg(m_debuggerCommand.toString()));
+    return QString::fromLatin1("%1:%2.%3.%4")
+               .arg(i).arg(m_compilerPath)
+               .arg(m_targetAbi.toString()).arg(m_debuggerCommand.toString());
 }
 
 QString GccToolChain::typeName() const
@@ -341,7 +341,6 @@ void GccToolChain::setTargetAbi(const Abi &abi)
 
     updateSupportedAbis();
     m_targetAbi = abi;
-    updateId();
     toolChainUpdated();
 }
 
@@ -389,7 +388,6 @@ void GccToolChain::setDebuggerCommand(const Utils::FileName &d)
     if (m_debuggerCommand == d)
         return;
     m_debuggerCommand = d;
-    updateId();
     toolChainUpdated();
 }
 
@@ -469,7 +467,7 @@ void GccToolChain::setCompilerPath(const QString &path)
         if (resetDisplayName)
             setDisplayName(defaultDisplayName());
     }
-    updateId(); // Will trigger toolChainUpdated()!
+    toolChainUpdated();
 }
 
 QString GccToolChain::compilerPath() const
@@ -511,7 +509,6 @@ bool GccToolChain::fromMap(const QVariantMap &data)
         m_supportedAbis.append(abi);
     }
     m_debuggerCommand = Utils::FileName::fromString(data.value(QLatin1String(debuggerCommandKeyC)).toString());
-    updateId();
     return true;
 }
 
diff --git a/src/plugins/projectexplorer/gcctoolchain.h b/src/plugins/projectexplorer/gcctoolchain.h
index b39c71f23dc..7e11bed0eaf 100644
--- a/src/plugins/projectexplorer/gcctoolchain.h
+++ b/src/plugins/projectexplorer/gcctoolchain.h
@@ -54,6 +54,8 @@ class LinuxIccToolChainFactory;
 class PROJECTEXPLORER_EXPORT GccToolChain : public ToolChain
 {
 public:
+    QString legacyId() const;
+
     QString typeName() const;
     Abi targetAbi() const;
     QString version() const;
@@ -89,8 +91,6 @@ protected:
 
     QString defaultDisplayName() const;
 
-    void updateId();
-
     virtual QList<Abi> detectSupportedAbis() const;
     virtual QString detectVersion() const;
 
diff --git a/src/plugins/projectexplorer/msvctoolchain.cpp b/src/plugins/projectexplorer/msvctoolchain.cpp
index 8abbf8df1d7..543aaec3ef8 100644
--- a/src/plugins/projectexplorer/msvctoolchain.cpp
+++ b/src/plugins/projectexplorer/msvctoolchain.cpp
@@ -288,7 +288,6 @@ MsvcToolChain::MsvcToolChain(const QString &name, const Abi &abi,
 {
     Q_ASSERT(!name.isEmpty());
 
-    updateId();
     setDisplayName(name);
 }
 
@@ -306,7 +305,7 @@ MsvcToolChain *MsvcToolChain::readFromMap(const QVariantMap &data)
     return 0;
 }
 
-void MsvcToolChain::updateId()
+QString MsvcToolChain::legacyId() const
 {
     const QChar colon = QLatin1Char(':');
     QString id = QLatin1String(Constants::MSVC_TOOLCHAIN_ID);
@@ -316,7 +315,7 @@ void MsvcToolChain::updateId()
     id += m_varsBatArg;
     id += colon;
     id += m_debuggerCommand.toString();
-    setId(id);
+    return id;
 }
 
 QString MsvcToolChain::typeName() const
@@ -356,7 +355,6 @@ bool MsvcToolChain::fromMap(const QVariantMap &data)
     m_debuggerCommand = Utils::FileName::fromString(data.value(QLatin1String(debuggerCommandKeyC)).toString());
     const QString abiString = data.value(QLatin1String(supportedAbiKeyC)).toString();
     m_abi = Abi(abiString);
-    updateId();
 
     return !m_vcvarsBat.isEmpty() && m_abi.isValid();
 }
diff --git a/src/plugins/projectexplorer/msvctoolchain.h b/src/plugins/projectexplorer/msvctoolchain.h
index 5ad742fc13a..bc51c189d4b 100644
--- a/src/plugins/projectexplorer/msvctoolchain.h
+++ b/src/plugins/projectexplorer/msvctoolchain.h
@@ -56,6 +56,7 @@ public:
 
     MsvcToolChain(const QString &name, const Abi &abi,
                   const QString &varsBat, const QString &varsBatArg, bool autodetect = false);
+    QString legacyId() const;
 
     static MsvcToolChain *readFromMap(const QVariantMap &data);
 
@@ -79,7 +80,6 @@ protected:
 
 private:
     MsvcToolChain();
-    void updateId();
 
     QString m_varsBatArg; // Argument
 };
diff --git a/src/plugins/projectexplorer/toolchain.cpp b/src/plugins/projectexplorer/toolchain.cpp
index 517756e2b91..cad5f70b7a0 100644
--- a/src/plugins/projectexplorer/toolchain.cpp
+++ b/src/plugins/projectexplorer/toolchain.cpp
@@ -38,9 +38,11 @@
 #include <utils/environment.h>
 
 #include <QtCore/QCoreApplication>
+#include <QtCore/QUuid>
 
 static const char ID_KEY[] = "ProjectExplorer.ToolChain.Id";
 static const char DISPLAY_NAME_KEY[] = "ProjectExplorer.ToolChain.DisplayName";
+static const char AUTODETECT_KEY[] = "ProjectExplorer.ToolChain.Autodetect";
 
 namespace ProjectExplorer {
 namespace Internal {
@@ -53,9 +55,22 @@ class ToolChainPrivate
 {
 public:
     ToolChainPrivate(const QString &id, bool autodetect) :
-        m_id(id),
         m_autodetect(autodetect)
-    { Q_ASSERT(!id.isEmpty()); }
+    {
+        m_id = createId(id);
+    }
+
+    static QString createId(const QString &id)
+    {
+        QString newId = id;
+
+        QUuid uuid(id.mid(id.indexOf(":") + 1));
+        if (uuid.isNull()) {
+            newId = id.left(id.indexOf(':'));
+            newId.append(QLatin1Char(':') + QUuid::createUuid().toString());
+        }
+        return newId;
+    }
 
     QString m_id;
     bool m_autodetect;
@@ -141,7 +156,11 @@ bool ToolChain::operator == (const ToolChain &tc) const
     if (this == &tc)
         return true;
 
-    return id() == tc.id();
+    const QString thisId = id().left(id().indexOf(QLatin1Char(':')));
+    const QString tcId = tc.id().left(tc.id().indexOf(QLatin1Char(':')));
+
+    // We ignore displayname
+    return thisId == tcId && isAutoDetected() == tc.isAutoDetected();
 }
 
 /*!
@@ -153,25 +172,13 @@ bool ToolChain::operator == (const ToolChain &tc) const
 QVariantMap ToolChain::toMap() const
 {
     QVariantMap result;
-    if (isAutoDetected())
-        return result;
-
     result.insert(QLatin1String(ID_KEY), id());
     result.insert(QLatin1String(DISPLAY_NAME_KEY), displayName());
+    result.insert(QLatin1String(AUTODETECT_KEY), isAutoDetected());
 
     return result;
 }
 
-void ToolChain::setId(const QString &id)
-{
-    Q_ASSERT(!id.isEmpty());
-    if (d->m_id == id)
-        return;
-
-    d->m_id = id;
-    toolChainUpdated();
-}
-
 void ToolChain::toolChainUpdated()
 {
     ToolChainManager::instance()->notifyAboutUpdate(this);
@@ -193,9 +200,10 @@ void ToolChain::setAutoDetected(bool autodetect)
 
 bool ToolChain::fromMap(const QVariantMap &data)
 {
-    Q_ASSERT(!isAutoDetected());
-    // do not read the id: That is already set anyway.
     d->m_displayName = data.value(QLatin1String(DISPLAY_NAME_KEY)).toString();
+    // make sure we have new style ids:
+    d->m_id = Internal::ToolChainPrivate::createId(data.value(QLatin1String(ID_KEY)).toString());
+    d->m_autodetect = data.value(QLatin1String(AUTODETECT_KEY), false).toBool();
 
     return true;
 }
diff --git a/src/plugins/projectexplorer/toolchain.h b/src/plugins/projectexplorer/toolchain.h
index b63193a583e..61dc2b585c4 100644
--- a/src/plugins/projectexplorer/toolchain.h
+++ b/src/plugins/projectexplorer/toolchain.h
@@ -72,6 +72,8 @@ public:
 
     bool isAutoDetected() const;
     QString id() const;
+    // No need to implement this for new tool chains:
+    virtual QString legacyId() const { return QString(); }
 
     virtual QString typeName() const = 0;
     virtual Abi targetAbi() const = 0;
@@ -105,8 +107,6 @@ protected:
     ToolChain(const QString &id, bool autoDetect);
     explicit ToolChain(const ToolChain &);
 
-    void setId(const QString &id);
-
     void toolChainUpdated();
 
     // Make sure to call this method when deriving!
diff --git a/src/plugins/projectexplorer/toolchainmanager.cpp b/src/plugins/projectexplorer/toolchainmanager.cpp
index 08a37e7c4dd..7e334290bcf 100644
--- a/src/plugins/projectexplorer/toolchainmanager.cpp
+++ b/src/plugins/projectexplorer/toolchainmanager.cpp
@@ -110,22 +110,61 @@ ToolChainManager::ToolChainManager(QObject *parent) :
 
 void ToolChainManager::restoreToolChains()
 {
-    // Restore SDK settings first
+    QList<ToolChain *> tcsToRegister;
+    QList<ToolChain *> tcsToCheck;
+
+    // read all tool chains from SDK
     QFileInfo systemSettingsFile(Core::ICore::settings(QSettings::SystemScope)->fileName());
-    restoreToolChains(systemSettingsFile.absolutePath() + QLatin1String(TOOLCHAIN_FILENAME), true);
+    QList<ToolChain *> readTcs =
+            restoreToolChains(systemSettingsFile.absolutePath() + QLatin1String(TOOLCHAIN_FILENAME));
+    // make sure we mark these as autodetected!
+    foreach (ToolChain *tc, readTcs)
+        tc->setAutoDetected(true);
+
+    tcsToRegister = readTcs; // SDK TCs are always considered to be up-to-date, so no need to
+                             // recheck them.
+
+    // read all tool chains from user file
+    readTcs = restoreToolChains(settingsFileName());
+
+    foreach (ToolChain *tc, readTcs) {
+        if (tc->isAutoDetected())
+            tcsToCheck.append(tc);
+        else
+            tcsToRegister.append(tc);
+    }
+    readTcs.clear();
 
     // Then auto detect
+    QList<ToolChain *> detectedTcs;
     ExtensionSystem::PluginManager *pm = ExtensionSystem::PluginManager::instance();
     QList<ToolChainFactory *> factories = pm->getObjects<ToolChainFactory>();
-    // Autodetect tool chains:
-    foreach (ToolChainFactory *f, factories) {
-        QList<ToolChain *> tcs = f->autoDetect();
-        foreach (ToolChain *tc, tcs)
-            registerToolChain(tc);
+    foreach (ToolChainFactory *f, factories)
+        detectedTcs.append(f->autoDetect());
+
+    // Find/update autodetected tool chains:
+    ToolChain *toStore = 0;
+    foreach (ToolChain *currentDetected, detectedTcs) {
+        toStore = currentDetected;
+
+        // Check whether we had this TC stored and prefer the old one with the old id:
+        for (int i = 0; i < tcsToCheck.count(); ++i) {
+            if (*(tcsToCheck.at(i)) == *currentDetected) {
+                toStore = tcsToCheck.at(i);
+                tcsToCheck.removeAt(i);
+                delete currentDetected;
+                break;
+            }
+        }
+        registerToolChain(toStore);
     }
 
-    // Then restore user settings
-    restoreToolChains(settingsFileName(), false);
+    // Delete all loaded autodetected tool chains that were not rediscovered:
+    qDeleteAll(tcsToCheck);
+
+    // Store manual tool chains
+    foreach (ToolChain *tc, tcsToRegister)
+        registerToolChain(tc);
 }
 
 ToolChainManager::~ToolChainManager()
@@ -146,7 +185,7 @@ void ToolChainManager::saveToolChains()
 
     int count = 0;
     foreach (ToolChain *tc, d->m_toolChains) {
-        if (!tc->isAutoDetected() && tc->isValid()) {
+        if (tc->isValid()) {
             QVariantMap tmp = tc->toMap();
             if (tmp.isEmpty())
                 continue;
@@ -160,17 +199,19 @@ void ToolChainManager::saveToolChains()
     // Do not save default debuggers! Those are set by the SDK!
 }
 
-void ToolChainManager::restoreToolChains(const QString &fileName, bool autoDetected)
+QList<ToolChain *> ToolChainManager::restoreToolChains(const QString &fileName)
 {
+    QList<ToolChain *> result;
+
     PersistentSettingsReader reader;
     if (!reader.load(fileName))
-        return;
+        return result;
     QVariantMap data = reader.restoreValues();
 
     // Check version:
     int version = data.value(QLatin1String(TOOLCHAIN_FILE_VERSION_KEY), 0).toInt();
     if (version < 1)
-        return;
+        return result;
 
     // Read default debugger settings (if any)
     int count = data.value(QLatin1String(DEFAULT_DEBUGGER_COUNT_KEY)).toInt();
@@ -200,19 +241,18 @@ void ToolChainManager::restoreToolChains(const QString &fileName, bool autoDetec
         foreach (ToolChainFactory *f, factories) {
             if (f->canRestore(tcMap)) {
                 if (ToolChain *tc = f->restore(tcMap)) {
-                    tc->setAutoDetected(autoDetected);
-
-                    registerToolChain(tc);
+                    result.append(tc);
                     restored = true;
                     break;
                 }
             }
         }
         if (!restored)
-            qWarning("Warning: Unable to restore manual tool chain '%s' stored in %s.",
+            qWarning("Warning: Unable to restore tool chain '%s' stored in %s.",
                      qPrintable(ToolChainFactory::idFromMap(tcMap)),
                      qPrintable(QDir::toNativeSeparators(fileName)));
     }
+    return result;
 }
 
 QList<ToolChain *> ToolChainManager::toolChains() const
@@ -233,8 +273,11 @@ QList<ToolChain *> ToolChainManager::findToolChains(const Abi &abi) const
 
 ToolChain *ToolChainManager::findToolChain(const QString &id) const
 {
+    if (id.isEmpty())
+        return 0;
+
     foreach (ToolChain *tc, d->m_toolChains) {
-        if (tc->id() == id)
+        if (tc->id() == id || (!tc->legacyId().isEmpty() && tc->legacyId() == id))
             return tc;
     }
     return 0;
diff --git a/src/plugins/projectexplorer/toolchainmanager.h b/src/plugins/projectexplorer/toolchainmanager.h
index cff534d9b1a..31ab664e627 100644
--- a/src/plugins/projectexplorer/toolchainmanager.h
+++ b/src/plugins/projectexplorer/toolchainmanager.h
@@ -90,7 +90,7 @@ private:
     // Make sure the this is only called after all
     // Tool chain Factories are registered!
     void restoreToolChains();
-    void restoreToolChains(const QString &fileName, bool autoDetected = false);
+    QList<ToolChain *> restoreToolChains(const QString &fileName);
 
     void notifyAboutUpdate(ProjectExplorer::ToolChain *);
 
diff --git a/src/plugins/projectexplorer/wincetoolchain.cpp b/src/plugins/projectexplorer/wincetoolchain.cpp
index b3a0c05eb9f..a3f86c40190 100644
--- a/src/plugins/projectexplorer/wincetoolchain.cpp
+++ b/src/plugins/projectexplorer/wincetoolchain.cpp
@@ -261,7 +261,6 @@ WinCEToolChain::WinCEToolChain(const QString &name,
     Q_ASSERT(!m_includePath.isEmpty());
     Q_ASSERT(!m_libPath.isEmpty());
 
-    updateId();
     setDisplayName(name);
 }
 
@@ -279,7 +278,7 @@ WinCEToolChain *WinCEToolChain::readFromMap(const QVariantMap &data)
     return 0;
 }
 
-void WinCEToolChain::updateId()
+QString WinCEToolChain::legacyId() const
 {
     const QChar colon = QLatin1Char(':');
     QString id = QLatin1String(Constants::WINCE_TOOLCHAIN_ID);
@@ -293,7 +292,7 @@ void WinCEToolChain::updateId()
     id += m_libPath;
     id += colon;
     id += m_debuggerCommand.toString();
-    setId(id);
+    return id;
 }
 
 QString WinCEToolChain::typeName() const
@@ -355,7 +354,6 @@ bool WinCEToolChain::fromMap(const QVariantMap &data)
     m_debuggerCommand = Utils::FileName::fromString(data.value(QLatin1String(debuggerCommandKeyC)).toString());
     const QString abiString = data.value(QLatin1String(supportedAbiKeyC)).toString();
     m_abi = Abi(abiString);
-    updateId();
 
     return isValid();
 }
diff --git a/src/plugins/projectexplorer/wincetoolchain.h b/src/plugins/projectexplorer/wincetoolchain.h
index ff37f9bec1e..836c85f79c6 100644
--- a/src/plugins/projectexplorer/wincetoolchain.h
+++ b/src/plugins/projectexplorer/wincetoolchain.h
@@ -57,6 +57,8 @@ public:
                    const QString &libPath,
                    bool autodetect = false);
 
+    QString legacyId() const;
+
     static WinCEToolChain *readFromMap(const QVariantMap &data);
 
     QString typeName() const;
@@ -79,7 +81,6 @@ protected:
 
 private:
     WinCEToolChain();
-    void updateId();
 
     QString m_msvcVer;
     QString m_ceVer;
diff --git a/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.cpp b/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.cpp
index e3e80dc6e3a..9d04513868d 100644
--- a/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.cpp
+++ b/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.cpp
@@ -91,19 +91,6 @@ static Utils::Environment baseEnvironment(RvctToolChain *tc)
     return result;
 }
 
-static QString toString(const RvctToolChain::ArmVersion &v)
-{
-    switch (v)
-    {
-    case RvctToolChain::ARMv5:
-        return QString::fromAscii("armv5");
-    case RvctToolChain::ARMv6:
-        return QString::fromAscii("armv6");
-    default:
-        return QString::fromAscii("unknown");
-    }
-}
-
 // ==========================================================================
 // RvctToolChain
 // ==========================================================================
@@ -284,7 +271,7 @@ void RvctToolChain::setCompilerPath(const QString &path)
 
     m_compilerPath = path;
     m_version.reset();
-    updateId(); // Will trigger toolChainUpdated()!
+    toolChainUpdated();
 }
 
 QString RvctToolChain::compilerPath() const
@@ -365,11 +352,11 @@ bool RvctToolChain::fromMap(const QVariantMap &data)
     return isValid();
 }
 
-void RvctToolChain::updateId()
+QString RvctToolChain::legacyId() const
 {
     const QChar dot = QLatin1Char('.');
-    setId(QLatin1String(Constants::RVCT_TOOLCHAIN_ID) + QLatin1Char(':')
-          + m_compilerPath + dot + toString(m_armVersion) + dot + m_debuggerCommand.toString());
+    return QLatin1String(Constants::RVCT_TOOLCHAIN_ID) + QLatin1Char(':') + m_compilerPath + dot
+            + armVersionString(m_armVersion) + dot + m_debuggerCommand.toString();
 }
 
 QString RvctToolChain::varName(const QString &postFix) const
diff --git a/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.h b/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.h
index 9cf1488631b..3f0468beea0 100644
--- a/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.h
+++ b/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.h
@@ -84,6 +84,8 @@ public:
     QString typeName() const;
     ProjectExplorer::Abi targetAbi() const;
 
+    QString legacyId() const;
+
     bool isValid() const;
 
     QByteArray predefinedMacros() const;
@@ -115,7 +117,6 @@ public:
     bool fromMap(const QVariantMap &data);
 
 private:
-    void updateId();
     void setVersion(const RvctVersion &v) const;
 
     explicit RvctToolChain(bool autodetected = false);
diff --git a/src/plugins/qt4projectmanager/qt-s60/winscwtoolchain.cpp b/src/plugins/qt4projectmanager/qt-s60/winscwtoolchain.cpp
index 187ddda521a..f0ff7e7cfc1 100644
--- a/src/plugins/qt4projectmanager/qt-s60/winscwtoolchain.cpp
+++ b/src/plugins/qt4projectmanager/qt-s60/winscwtoolchain.cpp
@@ -147,6 +147,11 @@ ProjectExplorer::Abi WinscwToolChain::targetAbi() const
                                 ProjectExplorer::Abi::ElfFormat, 32);
 }
 
+QString WinscwToolChain::legacyId() const
+{
+    return QLatin1String(Constants::WINSCW_TOOLCHAIN_ID) + QLatin1Char(':')  + m_compilerPath;
+}
+
 bool WinscwToolChain::isValid() const
 {
     if (m_compilerPath.isEmpty())
@@ -286,7 +291,7 @@ void WinscwToolChain::setCompilerPath(const QString &path)
         return;
 
     m_compilerPath = path;
-    updateId(); // Will trigger topolChainUpdated()!
+    toolChainUpdated();
 }
 
 QString WinscwToolChain::compilerPath() const
@@ -294,11 +299,6 @@ QString WinscwToolChain::compilerPath() const
     return m_compilerPath;
 }
 
-void WinscwToolChain::updateId()
-{
-    setId(QLatin1String(Constants::WINSCW_TOOLCHAIN_ID) + QLatin1Char(':')  + m_compilerPath);
-}
-
 // --------------------------------------------------------------------------
 // ToolChainConfigWidget
 // --------------------------------------------------------------------------
diff --git a/src/plugins/qt4projectmanager/qt-s60/winscwtoolchain.h b/src/plugins/qt4projectmanager/qt-s60/winscwtoolchain.h
index 6db4a15a1bd..5dc78d16191 100644
--- a/src/plugins/qt4projectmanager/qt-s60/winscwtoolchain.h
+++ b/src/plugins/qt4projectmanager/qt-s60/winscwtoolchain.h
@@ -54,6 +54,7 @@ public:
 
     QString typeName() const;
     ProjectExplorer::Abi targetAbi() const;
+    QString legacyId() const;
 
     bool isValid() const;
 
@@ -84,8 +85,6 @@ public:
     QString compilerPath() const;
 
 private:
-    void updateId();
-
     explicit WinscwToolChain(bool);
 
     QStringList m_systemIncludePathes;
diff --git a/src/plugins/qt4projectmanager/qt4buildconfiguration.cpp b/src/plugins/qt4projectmanager/qt4buildconfiguration.cpp
index 79cddcaa144..f95bab29791 100644
--- a/src/plugins/qt4projectmanager/qt4buildconfiguration.cpp
+++ b/src/plugins/qt4projectmanager/qt4buildconfiguration.cpp
@@ -133,7 +133,6 @@ bool Qt4BuildConfiguration::fromMap(const QVariantMap &map)
 
     m_shadowBuild = map.value(QLatin1String(USE_SHADOW_BUILD_KEY), true).toBool();
     m_qtVersionId = map.value(QLatin1String(QT_VERSION_ID_KEY)).toInt();
-    ProjectExplorer::ToolChain *tc = toolChain();
     m_qmakeBuildConfiguration = QtSupport::BaseQtVersion::QmakeBuildConfigs(map.value(QLatin1String(BUILD_CONFIGURATION_KEY)).toInt());
     m_buildDirectory = map.value(QLatin1String(BUILD_DIRECTORY_KEY), defaultShadowBuildDirectory()).toString();
 
@@ -160,6 +159,7 @@ bool Qt4BuildConfiguration::fromMap(const QVariantMap &map)
 
     m_lastEmmitedBuildDirectory = buildDirectory();
 
+    ProjectExplorer::ToolChain *tc = toolChain();
     if (version && version->isValid()) {
         if (tc && !qt4Target()->possibleToolChains(this).contains(tc))
             setToolChain(0);
@@ -377,7 +377,7 @@ void Qt4BuildConfiguration::setQtVersion(QtSupport::BaseQtVersion *version)
 
 void Qt4BuildConfiguration::setToolChain(ProjectExplorer::ToolChain *tc)
 {
-    if (tc != 0 && !qt4Target()->possibleToolChains(this).contains(tc))
+    if (tc != 0 && m_qtVersionId > 0 && !qt4Target()->possibleToolChains(this).contains(tc))
         return;
 
     if (toolChain() == tc)