diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index d9764348..ec53bebb 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -1,20 +1,20 @@
 Contributing
 ------------
 
-To get started, <a href="https://www.clahub.com/agreements/platformio/platformio-core">sign the Contributor License Agreement</a>.
+To get started, <a href="https://cla-assistant.io/platformio/platformio-core">sign the Contributor License Agreement</a>.
 
 1. Fork the repository on GitHub.
 2. Clone repository `git clone --recursive https://github.com/YourGithubUsername/platformio-core.git`
 3. Run `pip install tox`
-4. Go to the root of project where is located `tox.ini` and run `tox -e py27`
+4. Go to the root of project where is located `tox.ini` and run `tox -e py37`
 5. Activate current development environment:
 
-   * Windows: `.tox\py27\Scripts\activate`
-   * Bash/ZSH: `source .tox/py27/bin/activate`
-   * Fish: `source .tox/py27/bin/activate.fish`
+   * Windows: `.tox\py37\Scripts\activate`
+   * Bash/ZSH: `source .tox/py37/bin/activate`
+   * Fish: `source .tox/py37/bin/activate.fish`
 
 6. Make changes to code, documentation, etc.
-7. Lint source code `make lint`
+7. Lint source code `make before-commit`
 8. Run the tests `make test`
 9. Build documentation `tox -e docs` (creates a directory _build under docs where you can find the html)
 10. Commit changes to your forked repository