diff --git a/tests/auto/corelib/text/qstring/tst_qstring.cpp b/tests/auto/corelib/text/qstring/tst_qstring.cpp
index 92b4a266404..b31c5dedb8b 100644
--- a/tests/auto/corelib/text/qstring/tst_qstring.cpp
+++ b/tests/auto/corelib/text/qstring/tst_qstring.cpp
@@ -351,7 +351,8 @@ private:
 
     class TransientDefaultLocale
     {
-        const QLocale prior; // Records what *was* the default before we set it.
+        // This default-constructed QLocale records what *was* the default before we changed it:
+        const QLocale prior = {};
     public:
         TransientDefaultLocale(const QLocale &transient) { revise(transient); }
         void revise(const QLocale &transient) { QLocale::setDefault(transient); }