diff --git a/tests/auto/corelib/serialization/qxmlstream/tst_qxmlstream.cpp b/tests/auto/corelib/serialization/qxmlstream/tst_qxmlstream.cpp
index c6b73ae7742..c64088d4774 100644
--- a/tests/auto/corelib/serialization/qxmlstream/tst_qxmlstream.cpp
+++ b/tests/auto/corelib/serialization/qxmlstream/tst_qxmlstream.cpp
@@ -1659,10 +1659,11 @@ static bool isValidSingleTextChar(const ushort c)
 
 void tst_QXmlStream::readBack() const
 {
-    for (ushort c = 0; c < std::numeric_limits<ushort>::max(); ++c) {
-        QBuffer buffer;
+    QBuffer buffer;
 
-        QVERIFY(buffer.open(QIODevice::WriteOnly));
+    for (ushort c = 0; c < std::numeric_limits<ushort>::max(); ++c) {
+
+        QVERIFY(buffer.open(QIODevice::WriteOnly|QIODevice::Truncate));
         QXmlStreamWriter writer(&buffer);
         writer.writeStartDocument();
         writer.writeTextElement("a", QString(QChar(c)));