diff --git a/docs/development_checklist.md b/docs/development_checklist.md
index fde0c140..ddcb4301 100644
--- a/docs/development_checklist.md
+++ b/docs/development_checklist.md
@@ -9,6 +9,6 @@ Before you commit any changes, check your work against these requirements:
 - New dependencies are added to `requirements_all.txt` (if applicable), using `python3 -m script.gen_requirements_all`
 - New codeowners are added to `CODEOWNERS` (if applicable), using `python3 -m script.hassfest`
 - The `.coveragerc` file is updated to exclude your platform if there are no tests available or your new code uses a third-party library for communication with the device, service, or sensor
-- The code is formatted using Black, as per these [guidelines](https://developers.home-assistant.io/blog/2019/07/31/black.html). This can be done running the command `black --fast homeassistant`.
+- The code is formatted using Black, as per these [guidelines](https://developers.home-assistant.io/blog/2019/07/31/black.html). This can be done running the command `black --fast homeassistant tests`.
 - Documentation is developed for [home-assistant.io](https://home-assistant.io/)
   - Visit the [website documentation](/documenting.md) for more information about contributing to [home-assistant.io](https://github.com/home-assistant/home-assistant.io).