--- a/src/qml/jsruntime/qv4value_p.h.orig	2015-08-23 09:15:03.157582462 +0200
+++ b/src/qml/jsruntime/qv4value_p.h	2015-08-23 09:19:46.516039994 +0200
@@ -103,8 +103,8 @@ struct Q_QML_PRIVATE_EXPORT Value
 #endif
 
 #ifdef QV4_USE_64_BIT_VALUE_ENCODING
-    Q_ALWAYS_INLINE Heap::Base *m() const { Heap::Base *b; memcpy(&b, &_val, 8); return b; }
-    Q_ALWAYS_INLINE void setM(Heap::Base *b) { memcpy(&_val, &b, 8); }
+    Q_ALWAYS_INLINE Heap::Base *m() const { Heap::Base *b; memcpy(&b, &_val, QT_POINTER_SIZE); return b; }
+    Q_ALWAYS_INLINE void setM(Heap::Base *b) { memcpy(&_val, &b, QT_POINTER_SIZE); }
 #else // !QV4_USE_64_BIT_VALUE_ENCODING
     Q_ALWAYS_INLINE Heap::Base *m() const { Heap::Base *b; quint32 v = value(); memcpy(&b, &v, 4); return b; }
     Q_ALWAYS_INLINE void setM(Heap::Base *b) { quint32 v; memcpy(&v, &b, 4); setValue(v); }