The symptom is this: ```console % make MODE=aarch64 o/aarch64/third_party/python failed to move output file /Users/joshin/src/cosmo/o/tmp/o_aarch64_third_party_python_python o/aarch64/third_party/python/python .cosmocc/3.3.3/bin/aarch64-linux-cosmo-objcopy -S o/aarch64/third_party/python/python.dbg o/aarch64/third_party/python/python consumed 8,805µs wall time ballooned to 12,544kb in size needed 7,492us cpu (66% kernel) caused 1,474 page faults (99% memcpy) 39 context switches (5% consensual) make: *** [build/rules.mk:27: o/aarch64/third_party/python/python] Error 90 ``` The cause seems to be that there is a `o/aarch64/third_party/python/Python` directory, and Mac filesystems are usually case-insensitive.