diff --git a/src/plugins/projectexplorer/abstractmsvctoolchain.cpp b/src/plugins/projectexplorer/abstractmsvctoolchain.cpp
index 02903718dc7..f32306f9b23 100644
--- a/src/plugins/projectexplorer/abstractmsvctoolchain.cpp
+++ b/src/plugins/projectexplorer/abstractmsvctoolchain.cpp
@@ -47,11 +47,11 @@ namespace ProjectExplorer {
 namespace Internal {
 
 
-AbstractMsvcToolChain::AbstractMsvcToolChain(const QByteArray &id,
+AbstractMsvcToolChain::AbstractMsvcToolChain(Core::Id typeId,
                                              Detection d,
                                              const Abi &abi,
                                              const QString& vcvarsBat) :
-    ToolChain(id, d),
+    ToolChain(typeId, d),
     m_lastEnvironment(Utils::Environment::systemEnvironment()),
     m_abi(abi),
     m_vcvarsBat(vcvarsBat)
@@ -62,8 +62,8 @@ AbstractMsvcToolChain::AbstractMsvcToolChain(const QByteArray &id,
     Q_ASSERT(!m_vcvarsBat.isEmpty());
 }
 
-AbstractMsvcToolChain::AbstractMsvcToolChain(const QByteArray &id, Detection d) :
-    ToolChain(id, d),
+AbstractMsvcToolChain::AbstractMsvcToolChain(Core::Id typeId, Detection d) :
+    ToolChain(typeId, d),
     m_lastEnvironment(Utils::Environment::systemEnvironment())
 { }
 
diff --git a/src/plugins/projectexplorer/abstractmsvctoolchain.h b/src/plugins/projectexplorer/abstractmsvctoolchain.h
index 8797d69945f..c7017b7a999 100644
--- a/src/plugins/projectexplorer/abstractmsvctoolchain.h
+++ b/src/plugins/projectexplorer/abstractmsvctoolchain.h
@@ -44,8 +44,8 @@ namespace Internal {
 class PROJECTEXPLORER_EXPORT AbstractMsvcToolChain : public ToolChain
 {
 public:
-    explicit AbstractMsvcToolChain(const QByteArray &id, Detection d, const Abi &abi, const QString& vcvarsBat);
-    explicit AbstractMsvcToolChain(const QByteArray &id, Detection d);
+    explicit AbstractMsvcToolChain(Core::Id typeId, Detection d, const Abi &abi, const QString& vcvarsBat);
+    explicit AbstractMsvcToolChain(Core::Id typeId, Detection d);
 
     Abi targetAbi() const override;
 
diff --git a/src/plugins/projectexplorer/gcctoolchain.cpp b/src/plugins/projectexplorer/gcctoolchain.cpp
index 343a6109333..80b3bde2f3c 100644
--- a/src/plugins/projectexplorer/gcctoolchain.cpp
+++ b/src/plugins/projectexplorer/gcctoolchain.cpp
@@ -248,8 +248,8 @@ GccToolChain::GccToolChain(Detection d) :
     ToolChain(Constants::GCC_TOOLCHAIN_ID, d)
 { }
 
-GccToolChain::GccToolChain(const QByteArray &id, Detection d) :
-    ToolChain(id, d)
+GccToolChain::GccToolChain(Core::Id typeId, Detection d) :
+    ToolChain(typeId, d)
 { }
 
 void GccToolChain::setCompilerCommand(const FileName &path)
diff --git a/src/plugins/projectexplorer/gcctoolchain.h b/src/plugins/projectexplorer/gcctoolchain.h
index 8cf7029e988..d63c71e508d 100644
--- a/src/plugins/projectexplorer/gcctoolchain.h
+++ b/src/plugins/projectexplorer/gcctoolchain.h
@@ -57,7 +57,7 @@ class LinuxIccToolChainFactory;
 class PROJECTEXPLORER_EXPORT GccToolChain : public ToolChain
 {
 public:
-    GccToolChain(const QByteArray &id, Detection d);
+    GccToolChain(Core::Id typeId, Detection d);
     QString type() const override;
     QString typeDisplayName() const override;
     Abi targetAbi() const override;
diff --git a/src/plugins/projectexplorer/toolchain.cpp b/src/plugins/projectexplorer/toolchain.cpp
index 2c8be620b6c..75082a69402 100644
--- a/src/plugins/projectexplorer/toolchain.cpp
+++ b/src/plugins/projectexplorer/toolchain.cpp
@@ -36,6 +36,7 @@
 #include "task.h"
 
 #include <utils/fileutils.h>
+#include <utils/qtcassert.h>
 
 #include <QCoreApplication>
 #include <QUuid>
@@ -56,20 +57,14 @@ class ToolChainPrivate
 public:
     typedef ToolChain::Detection Detection;
 
-    explicit ToolChainPrivate(const QByteArray &id, Detection d) :
+    explicit ToolChainPrivate(Core::Id typeId, Detection d) :
+        m_id(QUuid::createUuid().toByteArray()),
+        m_typeId(typeId),
         m_detection(d)
-    {
-        m_id = createId(id);
-    }
-
-    static QByteArray createId(const QByteArray &id)
-    {
-        QByteArray newId = id.left(id.indexOf(':'));
-        newId.append(':' + QUuid::createUuid().toByteArray());
-        return newId;
-    }
+    { }
 
     QByteArray m_id;
+    Core::Id m_typeId;
     Detection m_detection;
     mutable QString m_displayName;
 };
@@ -84,12 +79,12 @@ public:
 
 // --------------------------------------------------------------------------
 
-ToolChain::ToolChain(const QByteArray &id, Detection d) :
-    d(new Internal::ToolChainPrivate(id, d))
+ToolChain::ToolChain(Core::Id typeId, Detection d) :
+    d(new Internal::ToolChainPrivate(typeId, d))
 { }
 
 ToolChain::ToolChain(const ToolChain &other) :
-    d(new Internal::ToolChainPrivate(other.d->m_id, ManualDetection))
+    d(new Internal::ToolChainPrivate(other.d->m_typeId, ManualDetection))
 {
     // leave the autodetection bit at false.
     d->m_displayName = QCoreApplication::translate("ProjectExplorer::ToolChain", "Clone of %1")
@@ -137,6 +132,11 @@ Utils::FileName ToolChain::suggestedDebugger() const
     return ToolChainManager::defaultDebugger(targetAbi());
 }
 
+Core::Id ToolChain::typeId() const
+{
+    return d->m_typeId;
+}
+
 bool ToolChain::canClone() const
 {
     return true;
@@ -147,11 +147,8 @@ bool ToolChain::operator == (const ToolChain &tc) const
     if (this == &tc)
         return true;
 
-    const QByteArray thisId = id().left(id().indexOf(':'));
-    const QByteArray tcId = tc.id().left(tc.id().indexOf(':'));
-
     // We ignore displayname
-    return thisId == tcId && isAutoDetected() == tc.isAutoDetected();
+    return typeId() == tc.typeId() && isAutoDetected() == tc.isAutoDetected();
 }
 
 /*!
@@ -163,7 +160,8 @@ bool ToolChain::operator == (const ToolChain &tc) const
 QVariantMap ToolChain::toMap() const
 {
     QVariantMap result;
-    result.insert(QLatin1String(ID_KEY), QString::fromUtf8(id()));
+    QString idToSave = d->m_typeId.toString() + QLatin1Char(':') + QString::fromUtf8(id());
+    result.insert(QLatin1String(ID_KEY), idToSave);
     result.insert(QLatin1String(DISPLAY_NAME_KEY), displayName());
     result.insert(QLatin1String(AUTODETECT_KEY), isAutoDetected());
 
@@ -192,8 +190,14 @@ void ToolChain::setDetection(ToolChain::Detection de)
 bool ToolChain::fromMap(const QVariantMap &data)
 {
     d->m_displayName = data.value(QLatin1String(DISPLAY_NAME_KEY)).toString();
+
     // make sure we have new style ids:
-    d->m_id = data.value(QLatin1String(ID_KEY)).toByteArray();
+    const QString id = data.value(QLatin1String(ID_KEY)).toString();
+    int pos = id.indexOf(QLatin1Char(':'));
+    QTC_ASSERT(pos > 0, return false);
+    d->m_typeId = Core::Id::fromString(id.left(pos));
+    d->m_id = id.mid(pos).toUtf8();
+
     const bool autoDetect = data.value(QLatin1String(AUTODETECT_KEY), false).toBool();
     d->m_detection = autoDetect ? AutoDetectionFromSettings : ManualDetection;
 
@@ -262,11 +266,6 @@ QByteArray ToolChainFactory::idFromMap(const QVariantMap &data)
     return data.value(QLatin1String(ID_KEY)).toByteArray();
 }
 
-void ToolChainFactory::idToMap(QVariantMap &data, const QString id)
-{
-    data.insert(QLatin1String(ID_KEY), id);
-}
-
 void ToolChainFactory::autoDetectionToMap(QVariantMap &data, bool detected)
 {
     data.insert(QLatin1String(AUTODETECT_KEY), detected);
diff --git a/src/plugins/projectexplorer/toolchain.h b/src/plugins/projectexplorer/toolchain.h
index dd31161a017..8d6f23dc45d 100644
--- a/src/plugins/projectexplorer/toolchain.h
+++ b/src/plugins/projectexplorer/toolchain.h
@@ -83,6 +83,7 @@ public:
     virtual Utils::FileName suggestedDebugger() const;
 
     virtual QString type() const = 0;
+    Core::Id typeId() const;
     virtual QString typeDisplayName() const = 0;
     virtual Abi targetAbi() const = 0;
 
@@ -157,7 +158,7 @@ public:
     virtual QVariantMap toMap() const;
     virtual QList<Task> validateKit(const Kit *k) const;
 protected:
-    explicit ToolChain(const QByteArray &id, Detection d);
+    explicit ToolChain(Core::Id typeId, Detection d);
     explicit ToolChain(const ToolChain &);
 
     void toolChainUpdated();
@@ -191,7 +192,6 @@ public:
     virtual ToolChain *restore(const QVariantMap &data);
 
     static QByteArray idFromMap(const QVariantMap &data);
-    static void idToMap(QVariantMap &data, const QString id);
     static void autoDetectionToMap(QVariantMap &data, bool detected);
 
 protected:
diff --git a/src/plugins/projectexplorer/toolchainmanager.cpp b/src/plugins/projectexplorer/toolchainmanager.cpp
index f59050c2d2d..22615ae7e27 100644
--- a/src/plugins/projectexplorer/toolchainmanager.cpp
+++ b/src/plugins/projectexplorer/toolchainmanager.cpp
@@ -299,7 +299,19 @@ ToolChain *ToolChainManager::findToolChain(const QByteArray &id)
     if (id.isEmpty())
         return 0;
 
-    return Utils::findOrDefault(d->m_toolChains, Utils::equal(&ToolChain::id, id));
+    ToolChain *tc = Utils::findOrDefault(d->m_toolChains, Utils::equal(&ToolChain::id, id));
+
+    // Compatibility with versions 3.5 and earlier:
+    if (!tc) {
+        const int pos = id.indexOf(':');
+        if (pos < 0)
+            return tc;
+
+        const QByteArray shortId = id.mid(pos + 1);
+
+        tc = Utils::findOrDefault(d->m_toolChains, Utils::equal(&ToolChain::id, shortId));
+    }
+    return tc;
 }
 
 FileName ToolChainManager::defaultDebugger(const Abi &abi)