Fixes #\<GitHub-issue-number\>.

Make sure all boxes are checked (add x inside the brackets) when you submit your contribution, remove this sentence before doing so.

- [ ] This PR is for the `dev` branch rather than for `master`.
- [ ] This PR is compliant with the [other contributing guidelines](https://github.com/nodemcu/nodemcu-firmware/blob/dev/CONTRIBUTING.md) as well (if not, please describe why).
- [ ] I have thoroughly tested my contribution.
- [ ] The code changes are reflected in the documentation at `docs/*`.

\<Description of and rationale behind this PR\>
