diff --git a/src/corelib/time/qtimezoneprivate_p.h b/src/corelib/time/qtimezoneprivate_p.h
index 129f0343b3..b37d9995e3 100644
--- a/src/corelib/time/qtimezoneprivate_p.h
+++ b/src/corelib/time/qtimezoneprivate_p.h
@@ -243,6 +243,7 @@ public:
 
     QIcuTimeZonePrivate *clone() const override;
 
+    using QTimeZonePrivate::displayName;
     QString displayName(QTimeZone::TimeType timeType, QTimeZone::NameType nameType,
                         const QLocale &locale) const override;
     QString abbreviation(qint64 atMSecsSinceEpoch) const override;
@@ -353,7 +354,12 @@ private:
     Data dataForTzTransition(QTzTransitionTime tran) const;
     Data dataFromRule(QTzTransitionRule rule, qint64 msecsSinceEpoch) const;
 #if QT_CONFIG(icu)
-    mutable QSharedDataPointer<QTimeZonePrivate> m_icu;
+# ifdef __cpp_lib_is_final
+    static_assert(std::is_final<QIcuTimeZonePrivate>::value,
+                  "if QIcuTimeZonePrivate isn't final, we may need to specialize "
+                  "QExplicitlySharedDataPointer::clone() to call QTimeZonePrivate::clone()");
+# endif
+    mutable QExplicitlySharedDataPointer<const QIcuTimeZonePrivate> m_icu;
 #endif
     QTzTimeZoneCacheEntry cached_data;
     QList<QTzTransitionTime> tranCache() const { return cached_data.m_tranTimes; }