diff --git a/src/corelib/kernel/qmetaobjectbuilder_p.h b/src/corelib/kernel/qmetaobjectbuilder_p.h
index 110aaf9ce2..3a1b43c3ed 100644
--- a/src/corelib/kernel/qmetaobjectbuilder_p.h
+++ b/src/corelib/kernel/qmetaobjectbuilder_p.h
@@ -323,7 +323,7 @@ private:
 class Q_CORE_EXPORT QMetaStringTable
 {
 public:
-    QMetaStringTable(const QByteArray &className);
+    explicit QMetaStringTable(const QByteArray &className);
 
     int enter(const QByteArray &value);