diff -r 5dc02b23752f -r 3e2da88830cd src/corelib/kernel/qmetaobject.cpp
--- a/src/corelib/kernel/qmetaobject.cpp	Tue Jul 06 15:10:48 2010 +0300
+++ b/src/corelib/kernel/qmetaobject.cpp	Wed Aug 18 10:37:55 2010 +0300
@@ -1454,6 +1454,11 @@
     If the "compute" slot does not take exactly one QString, one int
     and one double in the specified order, the call will fail.
 
+    \warning this method will not test the validity of the arguments: \a object
+    must be an instance of the class of the QMetaObject of which this QMetaMethod
+    has been constructed with.  The arguments must have the same type as the ones
+    expected by the method, else, the behaviour is undefined.
+
     \sa Q_ARG(), Q_RETURN_ARG(), qRegisterMetaType(), QMetaObject::invokeMethod()
 */
 bool QMetaMethod::invoke(QObject *object,
@@ -1473,6 +1478,8 @@
     if (!object || !mobj)
         return false;
 
+    Q_ASSERT(mobj->cast(object));
+
     // check return type
     if (returnValue.data()) {
         const char *retType = typeName();