[webkit-dev] JSImmediate.h 64 bit compatibility problem?

I see the following code, which works for 32 bit but not 64 bit. Is there another file or function somewhere that's for 64 bit? static bool isNegative(const JSValue* v) { ASSERT(isNumber(v)); return reinterpret_cast<uintptr_t>(v) & 0x80000000; }