diff --git a/src/corelib/tools/qtimezone.h b/src/corelib/tools/qtimezone.h
index 3f0d1ee9e7..cbc4f3e4ad 100644
--- a/src/corelib/tools/qtimezone.h
+++ b/src/corelib/tools/qtimezone.h
@@ -78,8 +78,8 @@ public:
 
     QTimeZone();
     explicit QTimeZone(const QByteArray &olsenId);
-    QTimeZone(int offsetSeconds);
-    QTimeZone(const QByteArray &zoneId, int offsetSeconds, const QString &name,
+    explicit QTimeZone(int offsetSeconds);
+    /*implicit*/ QTimeZone(const QByteArray &zoneId, int offsetSeconds, const QString &name,
               const QString &abbreviation, QLocale::Country country = QLocale::AnyCountry,
               const QString &comment = QString());
     QTimeZone(const QTimeZone &other);