diff --git a/src/corelib/kernel/qmetaobject.cpp b/src/corelib/kernel/qmetaobject.cpp
index b584c403fe8..d007d050501 100644
--- a/src/corelib/kernel/qmetaobject.cpp
+++ b/src/corelib/kernel/qmetaobject.cpp
@@ -192,6 +192,7 @@ public:
     inline int ownConstructorMethodIndex() const;
 
 private:
+    void checkMethodMetaTypeConsistency(const QtPrivate::QMetaTypeInterface *iface, int index) const;
     QMetaMethodPrivate();
 };
 } // unnamed namespace
@@ -1786,18 +1787,32 @@ int QMetaMethodPrivate::parameterCount() const
     return data.argc();
 }
 
-static inline void
-checkMethodMetaTypeConsistency(const QtPrivate::QMetaTypeInterface *iface, uint typeInfo)
+inline void
+QMetaMethodPrivate::checkMethodMetaTypeConsistency(const QtPrivate::QMetaTypeInterface *iface,
+                                                   int index) const
 {
+    uint typeInfo = parameterTypeInfo(index);
     QMetaType mt(iface);
     if (iface) {
         if ((typeInfo & IsUnresolvedType) == 0)
             Q_ASSERT(mt.id() == int(typeInfo & TypeNameIndexMask));
         Q_ASSERT(mt.name());
     } else {
-        // prior to Qt 6.5, the meta object did not record interfaces for void
-        // (obviously only the return type may be void)
-        Q_ASSERT(typeInfo & IsUnresolvedType || typeInfo == QMetaType::Void);
+        // The iface can only be null for a parameter if that parameter is a
+        // const-ref to a forward-declared type. Since primitive types are
+        // never incomplete, we can assert it's not one of them.
+
+#define ASSERT_NOT_PRIMITIVE_TYPE(TYPE, METATYPEID, NAME)           \
+        Q_ASSERT(typeInfo != QMetaType::TYPE);
+        QT_FOR_EACH_STATIC_PRIMITIVE_NON_VOID_TYPE(ASSERT_NOT_PRIMITIVE_TYPE)
+#undef ASSERT_NOT_PRIMITIVE_TYPE
+        Q_ASSERT(typeInfo != QMetaType::QObjectStar);
+
+        // Prior to Qt 6.4 we failed to record void and void*
+        if (priv(mobj->d.data)->revision >= 11) {
+            Q_ASSERT(typeInfo != QMetaType::Void);
+            Q_ASSERT(typeInfo != QMetaType::VoidStar);
+        }
     }
 }
 
@@ -1820,7 +1835,7 @@ const QtPrivate::QMetaTypeInterface *QMetaMethodPrivate::returnMetaTypeInterface
         return nullptr;         // constructors don't have return types
 
     const QtPrivate::QMetaTypeInterface *iface =  mobj->d.metaTypes[data.metaTypeOffset()];
-    checkMethodMetaTypeConsistency(iface, parameterTypeInfo(-1));
+    checkMethodMetaTypeConsistency(iface, -1);
     return iface;
 }
 
@@ -1831,7 +1846,7 @@ const QtPrivate::QMetaTypeInterface * const *QMetaMethodPrivate::parameterMetaTy
     const auto ifaces = &mobj->d.metaTypes[data.metaTypeOffset() + offset];
 
     for (int i = 0; i < parameterCount(); ++i)
-        checkMethodMetaTypeConsistency(ifaces[i], parameterTypeInfo(i));
+        checkMethodMetaTypeConsistency(ifaces[i], i);
 
     return ifaces;
 }
diff --git a/tests/auto/corelib/kernel/qmetaobject/forwarddeclared.cpp b/tests/auto/corelib/kernel/qmetaobject/forwarddeclared.cpp
index 8772bc4e613..d2477f86f05 100644
--- a/tests/auto/corelib/kernel/qmetaobject/forwarddeclared.cpp
+++ b/tests/auto/corelib/kernel/qmetaobject/forwarddeclared.cpp
@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
 #include "forwarddeclared.h"
+#include "qeasingcurve.h"
 
 struct MyForwardDeclaredType { };
 static MyForwardDeclaredType t;
@@ -15,3 +16,18 @@ MyForwardDeclaredType *getForwardDeclaredPointer() noexcept
 {
     return &t;
 }
+
+QT_BEGIN_NAMESPACE
+
+const QEasingCurve &getEasingCurve() noexcept
+{
+    return *getEasingCurvePointer();
+}
+
+QEasingCurve *getEasingCurvePointer() noexcept
+{
+    static QEasingCurve curve;
+    return &curve;
+}
+
+QT_END_NAMESPACE
diff --git a/tests/auto/corelib/kernel/qmetaobject/forwarddeclared.h b/tests/auto/corelib/kernel/qmetaobject/forwarddeclared.h
index 89fb0839c1a..83fdb0f8190 100644
--- a/tests/auto/corelib/kernel/qmetaobject/forwarddeclared.h
+++ b/tests/auto/corelib/kernel/qmetaobject/forwarddeclared.h
@@ -4,9 +4,18 @@
 #ifndef FORWARDDECLARED_H
 #define FORWARDDECLARED_H
 
+#include <qglobal.h>
+
 struct MyForwardDeclaredType;      // and ONLY forward-declared
 
 const MyForwardDeclaredType &getForwardDeclaredType() noexcept;
 MyForwardDeclaredType *getForwardDeclaredPointer() noexcept;
 
+QT_BEGIN_NAMESPACE
+class QEasingCurve;
+
+const QEasingCurve &getEasingCurve() noexcept;
+QEasingCurve *getEasingCurvePointer() noexcept;
+QT_END_NAMESPACE
+
 #endif // FORWARDDECLARED_H
diff --git a/tests/auto/corelib/kernel/qmetaobject/tst_qmetaobject.cpp b/tests/auto/corelib/kernel/qmetaobject/tst_qmetaobject.cpp
index 01f9617be1d..005b58fcb81 100644
--- a/tests/auto/corelib/kernel/qmetaobject/tst_qmetaobject.cpp
+++ b/tests/auto/corelib/kernel/qmetaobject/tst_qmetaobject.cpp
@@ -14,6 +14,14 @@ Q_DECLARE_METATYPE(const QMetaObject *)
 
 #include "forwarddeclared.h"
 
+#ifdef QEASINGCURVE_H
+#  error "Please make sure qeasingcurve.h is not #include'd here! " \
+    "We need QEasingCurve to be only forward-declared."
+#endif
+QT_BEGIN_NAMESPACE
+class QEasingCurve;
+QT_END_NAMESPACE
+
 struct MyStruct
 {
     int i;
@@ -489,6 +497,7 @@ public slots:
     qint64 sl14();
     qlonglong *sl15(qlonglong *);
     MyForwardDeclaredType *sl16(MyForwardDeclaredType *);
+    void sl17(const QEasingCurve &curve);
 
     void overloadedSlot();
     void overloadedSlot(int, int);
@@ -605,6 +614,8 @@ MyForwardDeclaredType *QtTestObject::sl16(MyForwardDeclaredType *ptr)
     slotResult += "null";
     return getForwardDeclaredPointer();
 }
+void QtTestObject::sl17(const QEasingCurve &)
+{ slotResult = "sl17"; }
 
 void QtTestObject::overloadedSlot()
 { slotResult = "overloadedSlot"; }
@@ -783,6 +794,11 @@ void tst_QMetaObject::invokeMetaMember()
     QCOMPARE(forwardPtr, getForwardDeclaredPointer());
     QCOMPARE(obj.slotResult, QString("sl16:null"));
 
+    // forward-declared builtin
+    obj.slotResult.clear();
+    QVERIFY(QMetaObject::invokeMethod(&obj, "sl17", Q_ARG(QEasingCurve, getEasingCurve())));
+    QCOMPARE(obj.slotResult, "sl17");
+
     // test overloads
     QVERIFY(QMetaObject::invokeMethod(&obj, "overloadedSlot"));
     QCOMPARE(obj.slotResult, QString("overloadedSlot"));
@@ -919,6 +935,12 @@ void tst_QMetaObject::invokeQueuedMetaMember()
     qApp->processEvents(QEventLoop::AllEvents);
     QCOMPARE(obj.slotResult, QString("sl15"));
 
+    // forward-declared builtin
+    obj.slotResult.clear();
+    QVERIFY(QMetaObject::invokeMethod(&obj, "sl17", Qt::QueuedConnection, Q_ARG(QEasingCurve, getEasingCurve())));
+    qApp->processEvents(QEventLoop::AllEvents);
+    QCOMPARE(obj.slotResult, "sl17");
+
     // test overloads
     QVERIFY(QMetaObject::invokeMethod(&obj, "overloadedSlot", Qt::QueuedConnection));
     qApp->processEvents(QEventLoop::AllEvents);
@@ -1172,6 +1194,11 @@ void tst_QMetaObject::invokeBlockingQueuedMetaMember()
     QCOMPARE(forwardPtr, getForwardDeclaredPointer());
     QCOMPARE(obj.slotResult, QString("sl16:null"));
 
+    // forward-declared builtin
+    obj.slotResult.clear();
+    QVERIFY(QMetaObject::invokeMethod(&obj, "sl17", Qt::BlockingQueuedConnection, Q_ARG(QEasingCurve, getEasingCurve())));
+    QCOMPARE(obj.slotResult, "sl17");
+
     // test overloads
     QVERIFY(QMetaObject::invokeMethod(&obj, "overloadedSlot", Qt::BlockingQueuedConnection));
     QCOMPARE(obj.slotResult, QString("overloadedSlot"));
@@ -2183,4 +2210,7 @@ void tst_QMetaObject::notifySignalsInParentClass()
 }
 
 QTEST_MAIN(tst_QMetaObject)
+
+static_assert(!QtPrivate::is_complete<QEasingCurve, void>::value,
+    "QEasingCurve must only be forward-declared at this point");
 #include "tst_qmetaobject.moc"