diff --git a/src/plugins/coreplugin/id.cpp b/src/plugins/coreplugin/id.cpp
index 61f61144852..db3d7409b2b 100644
--- a/src/plugins/coreplugin/id.cpp
+++ b/src/plugins/coreplugin/id.cpp
@@ -53,16 +53,9 @@ namespace Core {
     in a more typesafe and faster manner than a plain \c QString or
     \c QByteArray would provide.
 
-    An id is internally represented as a 32 bit integer (its \c UID)
-    and associated with a plain 7-bit-clean ASCII name used
+    An id is associated with a plain 7-bit-clean ASCII name used
     for display and persistency.
 
-    Each plugin that is distributed as part of \QC has a
-    private range of 10000 UIDs that are guaranteed to be unique.
-
-    Third party plugins are advised to construct ids from their
-    string representation.
-
 */
 
 class StringHolder
@@ -85,8 +78,8 @@ public:
         }
     }
     int n;
-    uint h;
     const char *str;
+    quintptr h;
 };
 
 static bool operator==(const StringHolder &sh1, const StringHolder &sh2)
@@ -98,10 +91,10 @@ static bool operator==(const StringHolder &sh1, const StringHolder &sh2)
 
 static uint qHash(const StringHolder &sh)
 {
-    return sh.h;
+    return QT_PREPEND_NAMESPACE(qHash)(sh.h, 0);
 }
 
-struct IdCache : public QHash<StringHolder, int>
+struct IdCache : public QHash<StringHolder, quintptr>
 {
 #ifndef QTC_ALLOW_STATIC_LEAKS
     ~IdCache()
@@ -113,13 +106,12 @@ struct IdCache : public QHash<StringHolder, int>
 };
 
 
-static int firstUnusedId = Id::IdsPerPlugin * Id::ReservedPlugins;
-
-static QHash<int, StringHolder> stringFromId;
+static QHash<quintptr, StringHolder> stringFromId;
 static IdCache idFromString;
 
-static int theId(const char *str, int n = 0)
+static quintptr theId(const char *str, int n = 0)
 {
+    static quintptr firstUnusedId = 10 * 1000 * 1000;
     QTC_ASSERT(str && *str, return 0);
     StringHolder sh(str, n);
     int res = idFromString.value(sh, 0);
@@ -132,26 +124,20 @@ static int theId(const char *str, int n = 0)
     return res;
 }
 
-static int theId(const QByteArray &ba)
+static quintptr theId(const QByteArray &ba)
 {
     return theId(ba.constData(), ba.size());
 }
 
 /*!
-    \fn Core::Id::Id(int uid)
+    \fn Core::Id::Id(quintptr uid)
+    \internal
 
     Constructs an id given \a UID.
 
     The UID is an integer value that is unique within the running
     \QC process.
 
-    It is the callers responsibility to ensure the uniqueness of
-    the passed integer. The recommended approach is to use
-    \c{registerId()} with an value taken from the plugin's
-    private range.
-
-    \sa registerId()
-
 */
 
 /*!
@@ -333,7 +319,7 @@ bool Id::operator==(const char *name) const
 }
 
 // For debugging purposes
-CORE_EXPORT const char *nameForId(int id)
+CORE_EXPORT const char *nameForId(quintptr id)
 {
     return stringFromId.value(id).str;
 }
diff --git a/src/plugins/coreplugin/id.h b/src/plugins/coreplugin/id.h
index 29d7cb47a75..f2ad3476431 100644
--- a/src/plugins/coreplugin/id.h
+++ b/src/plugins/coreplugin/id.h
@@ -46,10 +46,8 @@ namespace Core {
 class CORE_EXPORT Id
 {
 public:
-    enum { IdsPerPlugin = 10000, ReservedPlugins = 1000 };
-
     Id() : m_id(0) {}
-    Id(const char *name);
+    Id(const char *name); // Good to use.
 
     Id withSuffix(int suffix) const;
     Id withSuffix(const char *suffix) const;
@@ -68,8 +66,8 @@ public:
     bool operator<(Id id) const { return m_id < id.m_id; }
     bool operator>(Id id) const { return m_id > id.m_id; }
     bool alphabeticallyBefore(Id other) const;
-    int uniqueIdentifier() const { return m_id; }
-    static Id fromUniqueIdentifier(int uid) { return Id(uid); }
+
+    quintptr uniqueIdentifier() const { return m_id; } // Avoid.
     static Id fromString(const QString &str); // FIXME: avoid.
     static Id fromName(const QByteArray &ba); // FIXME: avoid.
     static Id fromSetting(const QVariant &variant); // Good to use.
@@ -81,14 +79,13 @@ public:
 
 private:
     // Intentionally unimplemented
-    Id(const QLatin1String &);
-    // Force explicit use of fromUniqueIdentifier().
-    explicit Id(int uid) : m_id(uid) {}
+    Id(const QLatin1String &) = delete;
+    explicit Id(quintptr uid) : m_id(uid) {}
 
-    int m_id;
+    quintptr m_id;
 };
 
-inline uint qHash(Id id) { return id.uniqueIdentifier(); }
+inline uint qHash(Id id) { return static_cast<uint>(id.uniqueIdentifier()); }
 
 } // namespace Core