A null pointer is a boxed value in LuaJIT, therefore not nil. But it is equal to nil when compared with nil. local x = require('ffi').cast('void*', nil)

A null pointer is a boxed value in LuaJIT, therefore not nil. But it is equal to nil when compared with nil. local x = require('ffi').cast('void*', nil) if x and x == nil then print("x is truthy and nil at the same time") end