diff --git a/tests/auto/network/access/qnetworkreply/tst_qnetworkreply.cpp b/tests/auto/network/access/qnetworkreply/tst_qnetworkreply.cpp
index 2675df50036..05ee120f970 100644
--- a/tests/auto/network/access/qnetworkreply/tst_qnetworkreply.cpp
+++ b/tests/auto/network/access/qnetworkreply/tst_qnetworkreply.cpp
@@ -10116,13 +10116,20 @@ void tst_QNetworkReply::qtbug68821proxyError_data()
 
 void tst_QNetworkReply::qtbug68821proxyError()
 {
-    QTcpServer proxyServer;
-    QVERIFY(proxyServer.listen());
-    quint16 proxyPort = proxyServer.serverPort();
-    proxyServer.close();
+    auto getUnusedPort = []() -> std::optional<quint16> {
+        QTcpServer probeServer;
+        if (!probeServer.listen())
+            return std::nullopt;
+        // If we can listen on it, it was unused, and hopefully is also
+        // still unused after we stop listening.
+        return probeServer.serverPort();
+    };
+
+    auto proxyPort = getUnusedPort();
+    QVERIFY(proxyPort);
 
     QFETCH(QString, proxyHost);
-    QNetworkProxy proxy(QNetworkProxy::HttpProxy, proxyHost, proxyPort);
+    QNetworkProxy proxy(QNetworkProxy::HttpProxy, proxyHost, proxyPort.value());
 
     manager.setProxy(proxy);