diff --git a/src/corelib/kernel/qobject.h b/src/corelib/kernel/qobject.h
index 9916626a3ce..713a62c2499 100644
--- a/src/corelib/kernel/qobject.h
+++ b/src/corelib/kernel/qobject.h
@@ -241,8 +241,13 @@ public:
             types = QtPrivate::ConnectionTypes<typename SignalType::Arguments>::types();
 
         void **pSlot = nullptr;
-        if constexpr (std::is_member_function_pointer_v<std::decay_t<Func2>>)
+        if constexpr (std::is_member_function_pointer_v<std::decay_t<Func2>>) {
             pSlot = const_cast<void **>(reinterpret_cast<void *const *>(&slot));
+        } else {
+            Q_ASSERT_X((type & Qt::UniqueConnection) == 0, "",
+                       "QObject::connect: Unique connection requires the slot to be a pointer to "
+                       "a member function of a QObject subclass.");
+        }
 
         return connectImpl(sender, reinterpret_cast<void **>(&signal), context, pSlot,
                            QtPrivate::makeCallableObject<Func1>(std::forward<Func2>(slot)),
diff --git a/tests/auto/corelib/kernel/qobject/tst_qobject.cpp b/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
index a06238a494b..b626d0e3c4e 100644
--- a/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
+++ b/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
@@ -6429,11 +6429,46 @@ void tst_QObject::connectFunctorWithContextUnique()
     QVERIFY(QObject::connect(&sender, &SenderObject::signal1, &receiver, &ReceiverObject::slot1));
     receiver.count_slot1 = 0;
 
-    QTest::ignoreMessage(QtWarningMsg, "QObject::connect(SenderObject, ReceiverObject): unique connections require a pointer to member function of a QObject subclass");
+    QVERIFY(QObject::connect(&sender, &SenderObject::signal2, &receiver, &ReceiverObject::slot2));
+    receiver.count_slot2 = 0;
+
+    const auto oredType = Qt::ConnectionType(Qt::DirectConnection | Qt::UniqueConnection);
+
+    // Will assert in debug builds, so only test in release builds
+#if defined(QT_NO_DEBUG) && !defined(QT_FORCE_ASSERTS)
+    auto ignoreMsg = [] {
+        QTest::ignoreMessage(QtWarningMsg,
+                             "QObject::connect(SenderObject, ReceiverObject): unique connections "
+                             "require a pointer to member function of a QObject subclass");
+    };
+
+    ignoreMsg();
     QVERIFY(!QObject::connect(&sender, &SenderObject::signal1, &receiver, [&](){ receiver.slot1(); }, Qt::UniqueConnection));
 
+    ignoreMsg();
+    QVERIFY(!QObject::connect(
+        &sender, &SenderObject::signal2, &receiver, [&]() { receiver.slot2(); }, oredType));
+#endif
+
     sender.emitSignal1();
     QCOMPARE(receiver.count_slot1, 1);
+
+    sender.emitSignal2();
+    QCOMPARE(receiver.count_slot2, 1);
+
+    // Check connecting to PMF doesn't hit the assert
+
+    QVERIFY(QObject::connect(&sender, &SenderObject::signal3, &receiver, &ReceiverObject::slot3,
+                             Qt::UniqueConnection));
+    receiver.count_slot3 = 0;
+    sender.emitSignal3();
+    QCOMPARE(receiver.count_slot3, 1);
+
+    QVERIFY(QObject::connect(&sender, &SenderObject::signal4, &receiver, &ReceiverObject::slot4,
+                             oredType));
+    receiver.count_slot4 = 0;
+    sender.emitSignal4();
+    QCOMPARE(receiver.count_slot4, 1);
 }
 
 class MyFunctor