# Will the new M1 chip affect cmdstanR?

**URL:** <https://discourse.mc-stan.org/t/will-the-new-m1-chip-affect-cmdstanr/19379>\
**Category:** General\
**Created:** [November 19, 2020, 5:11am UTC](https://discourse.mc-stan.org/t/will-the-new-m1-chip-affect-cmdstanr/19379 "2020-11-19T05:11:33Z")\
**Posts on this page:** 1\
**Showing post:** 6

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**Author:** ![rok\_cesnovar](https://avatars.discourse-cdn.com/v4/letter/r/7bcc69/32.png) [@rok\_cesnovar](https://discourse.mc-stan.org/u/rok_cesnovar)\
**Post date:** [November 23, 2020, 4:52pm UTC](https://discourse.mc-stan.org/t/will-the-new-m1-chip-affect-cmdstanr/19379/6 "2020-11-23T16:52:30Z")

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A quick update:

A user reported that cmdstan via cmdstanr works OK after adding  
`CXX="arch -arch arm64e clang++"` to the makefile flags.

So for cmdstan you need to add the following to to `make/loca`l and rebuild cmdstan  
`CXX="arch -arch arm64e clang++"`

For cmdstanr you need to run

```
cmdstanr::cmdstan_make_local(cpp_options = list(CXX="arch -arch arm64e clang++"))
rebuild_cmdstan()

```

and then everything should work fine. The next cmdstan version will handle this automatically.

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_[View the full topic](https://discourse.mc-stan.org/t/will-the-new-m1-chip-affect-cmdstanr/19379)._