diff --git a/tests/auto/network/socket/qtcpserver/crashingServer/main.cpp b/tests/auto/network/socket/qtcpserver/crashingServer/main.cpp
index 1fe9f78a329..c14c429520e 100644
--- a/tests/auto/network/socket/qtcpserver/crashingServer/main.cpp
+++ b/tests/auto/network/socket/qtcpserver/crashingServer/main.cpp
@@ -26,16 +26,21 @@ int main(int argc, char *argv[])
 #endif
 
     QCoreApplication app(argc, argv);
+    if (argc < 1) {
+        fprintf(stderr, "Need a port number\n");
+        return 1;
+    }
 
+    int port = QByteArrayView(argv[1]).toInt();
     QTcpServer server;
-    if (!server.listen(QHostAddress::LocalHost, 49199)) {
+    if (!server.listen(QHostAddress::LocalHost, port)) {
         fprintf(stderr, "Failed to listen: %s\n", server.errorString().toLatin1().constData());
         if (server.serverError() == QTcpSocket::AddressInUseError) {
             // let's see if we can find the process that would be holding this
             // still open
 #ifdef Q_OS_LINUX
             static const char *ss_args[] = {
-                "ss", "-nap", "sport", "=", ":49199", nullptr
+                "ss", "-nap", "sport", "=", argv[1], nullptr
             };
             dup2(STDERR_FILENO, STDOUT_FILENO);
             execvp(ss_args[0], const_cast<char **>(ss_args));
diff --git a/tests/auto/network/socket/qtcpserver/tst_qtcpserver.cpp b/tests/auto/network/socket/qtcpserver/tst_qtcpserver.cpp
index e47c8f4654d..5c87a3f04b3 100644
--- a/tests/auto/network/socket/qtcpserver/tst_qtcpserver.cpp
+++ b/tests/auto/network/socket/qtcpserver/tst_qtcpserver.cpp
@@ -588,16 +588,25 @@ void tst_QTcpServer::addressReusable()
         QSKIP("No proxy support");
 #endif // QT_NO_NETWORKPROXY
     }
+
+    QTcpServer server;
+    QVERIFY(server.listen(QHostAddress::LocalHost, 0));
+    quint16 serverPort = server.serverPort();
+    qDebug() << "Got port" << serverPort;
+    server.close();     // cleanly close
+
+    QTest::qSleep(10);
+
     // The crashingServer process will crash once it gets a connection.
     QProcess process;
     QString processExe = crashingServerDir + "/crashingServer";
-    process.start(processExe);
+    process.start(processExe, { QString::number(serverPort) });
     QVERIFY2(process.waitForStarted(), qPrintable(
         QString::fromLatin1("Could not start %1: %2").arg(processExe, process.errorString())));
     QVERIFY2(process.waitForReadyRead(5000), qPrintable(process.readAllStandardError()));
 
     QTcpSocket socket;
-    socket.connectToHost(QHostAddress::LocalHost, 49199);
+    socket.connectToHost(QHostAddress::LocalHost, serverPort);
     QVERIFY(socket.waitForConnected(5000));
 
     QVERIFY(process.waitForFinished(30000));
@@ -605,8 +614,9 @@ void tst_QTcpServer::addressReusable()
     // Give the system some time.
     QTest::qSleep(10);
 
-    QTcpServer server;
-    QVERIFY(server.listen(QHostAddress::LocalHost, 49199));
+    // listen again
+    QVERIFY2(server.listen(QHostAddress::LocalHost, serverPort),
+             qPrintable(server.errorString()));
 #endif
 }