diff --git a/src/xml/dom/qdom.cpp b/src/xml/dom/qdom.cpp
index 2ac4c69b7f1..603704f9163 100644
--- a/src/xml/dom/qdom.cpp
+++ b/src/xml/dom/qdom.cpp
@@ -6197,12 +6197,28 @@ bool QDomDocument::setContent(const QByteArray &data, bool namespaceProcessing,
 
     This function reads the XML document from the IO device \a dev, returning
     true if the content was successfully parsed; otherwise returns \c false.
+
+    \note This method will try to open \a dev in read-only mode if it is not
+    already open. In that case, the caller is responsible for calling close.
+    This will change in Qt 7, which will no longer open \a dev. Applications
+    shoul therefore open the device themselves before calling setContent.
 */
 bool QDomDocument::setContent(QIODevice* dev, bool namespaceProcessing, QString *errorMsg, int *errorLine, int *errorColumn)
 {
     if (!impl)
         impl = new QDomDocumentPrivate();
 
+#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
+    if (!dev->isOpen()) {
+        qWarning("QDomDocument called with unopened QIODevice. "
+                 "This will not be supported in future Qt versions");
+        if (!dev->open(QIODevice::ReadOnly)) {
+            qWarning("QDomDocument::setContent: Failed to open device");
+            return false;
+        }
+    }
+#endif
+
     QXmlStreamReader streamReader(dev);
     streamReader.setNamespaceProcessing(namespaceProcessing);
     return IMPL->setContent(&streamReader, namespaceProcessing, errorMsg, errorLine, errorColumn);
diff --git a/tests/auto/xml/dom/qdom/tst_qdom.cpp b/tests/auto/xml/dom/qdom/tst_qdom.cpp
index c44626e1612..b1c9b2e9c9e 100644
--- a/tests/auto/xml/dom/qdom/tst_qdom.cpp
+++ b/tests/auto/xml/dom/qdom/tst_qdom.cpp
@@ -111,6 +111,7 @@ private slots:
     void checkIntOverflow() const;
     void setContentWhitespace() const;
     void setContentWhitespace_data() const;
+    void setContentUnopenedQIODevice() const;
 
     void taskQTBUG4595_dontAssertWhenDocumentSpecifiesUnknownEncoding() const;
     void cloneDTD_QTBUG8398() const;
@@ -1919,6 +1920,23 @@ void tst_QDom::setContentWhitespace_data() const
     QTest::newRow("data25") << QString::fromLatin1("\t\t\t\t<?xml version='1.0' ?><e/>")  << false;
 }
 
+void tst_QDom::setContentUnopenedQIODevice() const
+{
+    QByteArray data("<foo>bar</foo>");
+    QBuffer buffer(&data);
+
+    QDomDocument doc;
+
+    QTest::ignoreMessage(QtWarningMsg,
+                         "QDomDocument called with unopened QIODevice. "
+                         "This will not be supported in future Qt versions");
+
+    // Note: the check below is expected to fail in Qt 7.
+    // Fix the test and remove the obsolete code from setContent().
+    QVERIFY(doc.setContent(&buffer, true));
+    QCOMPARE(doc.toString().trimmed(), data);
+}
+
 void tst_QDom::taskQTBUG4595_dontAssertWhenDocumentSpecifiesUnknownEncoding() const
 {
     QString xmlWithUnknownEncoding("<?xml version='1.0' encoding='unknown-encoding'?>"