#define JSAPI_FS(name, nargs, flags) \ - JS_FS(#name, jsapi_native_##name, nargs, flags, 0) + JS_FS(#name, jsapi_native_##name, nargs, flags) That should probably extended into something like that: #ifdef JS_VERSION <= 150 JS_FS(#name, jsapi_native_##name, nargs, flags, 0) #else JS_FS(#name, jsapi_native_##name, nargs, flags) ( it looks like that 1.5 uses the same number of initial values as versions > 1.8.0 )