diff --git a/src/corelib/kernel/qmetaobject.cpp b/src/corelib/kernel/qmetaobject.cpp
index 4da62b73586..5f2fccfa5a8 100644
--- a/src/corelib/kernel/qmetaobject.cpp
+++ b/src/corelib/kernel/qmetaobject.cpp
@@ -26,6 +26,8 @@
 #include <ctype.h>
 #include <memory>
 
+#include <cstring>
+
 QT_BEGIN_NAMESPACE
 
 using namespace Qt::StringLiterals;
@@ -741,6 +743,31 @@ inline int QMetaObjectPrivate::indexOfMethodRelative(const QMetaObject **baseObj
     \sa constructor(), constructorCount(), normalizedSignature()
 */
 
+#if QT_DEPRECATED_SINCE(6, 10)
+Q_DECL_COLD_FUNCTION
+static int compat_indexOf(const char *what, const char *sig, const QMetaObject *mo,
+                          int (*indexOf)(const QMetaObject *, const char *))
+{
+    const QByteArray normalized = QByteArray(sig).replace("QVector<", "QList<");
+    const int i = indexOf(mo, normalized.data());
+    if (i >= 0) {
+        qWarning(R"(QMetaObject::indexOf%s: argument "%s" is not normalized, because it contains "QVector<". )"
+                 R"(Earlier versions of Qt 6 incorrectly normalized QVector< to QList<, silently. )"
+                 R"(This behavior is deprecated as of 6.10, and will be removed in a future version of Qt.)",
+                 what, sig);
+    }
+    return i;
+}
+
+#define INDEXOF_COMPAT(what, arg) \
+    do { \
+        if (i < 0 && Q_UNLIKELY(std::strstr(arg, "QVector<"))) \
+            i = compat_indexOf(#what, arg, this, &indexOf ## what ## _helper); \
+    } while (false)
+#else
+#define INDEXOF_COMPAT(what, arg)
+#endif // QT_DEPRECATED_SINCE(6, 10)
+
 static int indexOfConstructor_helper(const QMetaObject *mo, const char *constructor)
 {
     QArgumentTypeArray types;
@@ -752,6 +779,7 @@ int QMetaObject::indexOfConstructor(const char *constructor) const
 {
     Q_ASSERT(priv(d.data)->revision >= 7);
     int i = indexOfConstructor_helper(this, constructor);
+    INDEXOF_COMPAT(Constructor, constructor);
     return i;
 }
 
@@ -782,6 +810,7 @@ int QMetaObject::indexOfMethod(const char *method) const
 {
     const QMetaObject *m = this;
     int i = indexOfMethod_helper(m, method);
+    INDEXOF_COMPAT(Method, method);
     return i;
 }
 
@@ -804,7 +833,6 @@ static void argumentTypesFromString(const char *str, const char *end,
             ++str;
         }
         QByteArray argType(begin, str - begin);
-        argType.replace("QVector<", "QList<");
         types += QArgumentType(std::move(argType));
     }
 }
@@ -856,6 +884,7 @@ int QMetaObject::indexOfSignal(const char *signal) const
 {
     const QMetaObject *m = this;
     int i = indexOfSignal_helper(m, signal);
+    INDEXOF_COMPAT(Signal, signal);
     return i;
 }
 
@@ -912,9 +941,12 @@ int QMetaObject::indexOfSlot(const char *slot) const
 {
     const QMetaObject *m = this;
     int i = indexOfSlot_helper(m, slot);
+    INDEXOF_COMPAT(Slot, slot);
     return i;
 }
 
+#undef INDEXOF_COMPAT
+
 // same as indexOfSignalRelative but for slots.
 int QMetaObjectPrivate::indexOfSlotRelative(const QMetaObject **m,
                                             QByteArrayView name, int argc,
diff --git a/tests/auto/corelib/kernel/qmetaobject/tst_qmetaobject.cpp b/tests/auto/corelib/kernel/qmetaobject/tst_qmetaobject.cpp
index c44345c6ed7..a26a0b1a42a 100644
--- a/tests/auto/corelib/kernel/qmetaobject/tst_qmetaobject.cpp
+++ b/tests/auto/corelib/kernel/qmetaobject/tst_qmetaobject.cpp
@@ -40,6 +40,17 @@ Q_DECLARE_METATYPE(const QMetaObject *)
 
 using namespace Qt::StringLiterals;
 
+#if QT_DEPRECATED_SINCE(6, 10)
+static void eatIndexOfNonNormalizedWarning()
+{
+    static const QRegularExpression rx(R"(QMetaObject::indexOf(Constructor|Method|Signal|Slot): )"
+                                       R"(argument ".+" is not normalized, )"
+                                       R"(because it contains "QVector<"\.)"_L1);
+    QTest::ignoreMessage(QtWarningMsg, rx);
+}
+#define NORMALIZES_QVECTOR_QLIST
+#endif
+
 struct MyStruct
 {
     int i;
@@ -2470,12 +2481,8 @@ void tst_QMetaObject::customQVectorSuffix()
     QVERIFY(connect(this, SIGNAL(myQListChanged(MyQList<int>)),
                     &ctx, SLOT(deleteLater()))); // just some compatible slot...
 
-    // QMetaObject internally does s/QVector</QList</ indiscriminently, so the
-    // existing signal is not found:
-    QEXPECT_FAIL("", "Qt 6 QVector -> QList kludge getting in the way", Continue);
-    QTest::ignoreMessage(QtWarningMsg,
-                         QRegularExpression(R"(.*QObject::connect: No such signal )"
-                                            R"(tst_QMetaObject.*::myQVectorChanged\(MyQVector<double>\).*)"_L1));
+    // QMetaObject used to internally s/QVector</QList</ indiscriminently, so the
+    // existing signal was not found:
     QVERIFY(connect(this, SIGNAL(myQVectorChanged(MyQVector<double>)),
                     &ctx, SLOT(deleteLater()))); // just some compatible slot...
 }
@@ -2759,12 +2766,18 @@ void tst_QMetaObject::metaMethod()
     QCOMPARE(obj.slotResult, QString("sl5:12345"));
 
     // check Qt 6 QVector/QList alias:
+#ifdef NORMALIZES_QVECTOR_QLIST
+    eatIndexOfNonNormalizedWarning();
     index = QtTestObject::staticMetaObject.indexOfMethod("sl13v(QVector<QString>)");
     QVERIFY(index > 0);
+#endif
     index = QtTestObject::staticMetaObject.indexOfMethod("sl13v(QList<QString>)");
     QVERIFY(index > 0);
+#ifdef NORMALIZES_QVECTOR_QLIST
+    eatIndexOfNonNormalizedWarning();
     index = QtTestObject::staticMetaObject.indexOfMethod("sl13(QVector<QString>)");
     QVERIFY(index > 0);
+#endif
     index = QtTestObject::staticMetaObject.indexOfMethod("sl13(QList<QString>)");
     QVERIFY(index > 0);
     QMetaMethod sl13 = QtTestObject::staticMetaObject.method(index);
@@ -2781,14 +2794,20 @@ void tst_QMetaObject::metaMethod()
 
     index = QtTestObject::staticMetaObject.indexOfConstructor("QtTestObject(QObject*,QList<int>)");
     QVERIFY(index > 0);
+#ifdef NORMALIZES_QVECTOR_QLIST
+    eatIndexOfNonNormalizedWarning();
     index = QtTestObject::staticMetaObject.indexOfConstructor("QtTestObject(QObject*,QVector<int>)");
     QVERIFY(index > 0);
+#endif
     QCOMPARE(QtTestObject::staticMetaObject.constructor(index).methodSignature(),
              "QtTestObject(QObject*,QList<int>)");
     index = QtTestObject::staticMetaObject.indexOfConstructor("QtTestObject(QList<int>,QObject*)");
     QVERIFY(index > 0);
+#ifdef NORMALIZES_QVECTOR_QLIST
+    eatIndexOfNonNormalizedWarning();
     index = QtTestObject::staticMetaObject.indexOfConstructor("QtTestObject(QVector<int>,QObject*)");
     QVERIFY(index > 0);
+#endif
     QCOMPARE(QtTestObject::staticMetaObject.constructor(index).methodSignature(),
              "QtTestObject(QList<int>,QObject*)");
 }
@@ -2832,8 +2851,11 @@ void tst_QMetaObject::metaMethodNoMacro()
     QCOMPARE(obj.slotResult, QString("sl5:12345"));
 
     // check Qt 6 QVector/QList alias:
+#ifdef NORMALIZES_QVECTOR_QLIST
+    eatIndexOfNonNormalizedWarning();
     index = QtTestObject::staticMetaObject.indexOfMethod("sl13(QVector<QString>)");
     QVERIFY(index > 0);
+#endif
     index = QtTestObject::staticMetaObject.indexOfMethod("sl13(QList<QString>)");
     QVERIFY(index > 0);
     QMetaMethod sl13 = QtTestObject::staticMetaObject.method(index);
@@ -2878,8 +2900,11 @@ void tst_QMetaObject::indexOfMethod()
     QFETCH(QByteArray, name);
     QFETCH(bool, isSignal);
     QFETCH(const bool, found);
+#ifdef NORMALIZES_QVECTOR_QLIST
     QEXPECT_FAIL("myQListChanged(MyQVector<int>)", "Qt 6 QVector -> QList kludge getting in the way", Abort);
-    QEXPECT_FAIL("myQVectorChanged(MyQVector<double>)", "Qt 6 QVector -> QList kludge getting in the way", Abort);
+    if (qstrcmp(QTest::currentDataTag(), "myQListChanged(MyQVector<int>)") == 0)
+        eatIndexOfNonNormalizedWarning();
+#endif
     int idx = object->metaObject()->indexOfMethod(name);
     if (found)
         QVERIFY(idx >= 0);
@@ -3333,5 +3358,9 @@ void tst_QMetaObject::connectByMetaMethodToFreeFunction()
     QCOMPARE(emit o.sig1(u"foo"_s), u"foofoo"_s);
 }
 
+#ifdef NORMALIZES_QVECTOR_QLIST
+# undef NORMALIZES_QVECTOR_QLIST
+#endif
+
 QTEST_MAIN(tst_QMetaObject)
 #include "tst_qmetaobject.moc"