diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -127,7 +127,7 @@
 During submission of patches, arcanist will automatically run `arc lint` to
 enforce Bitcoin ABC code formatting standards, and often suggests changes.
 If code formatting tools do not install automatically on your system, you
-will have to install clang-format-7, autopep8 and flake8.
+will have to install clang-format-7, autopep8, flake8 and phpcs.
 
 To install clang-format-7 on Ubuntu (>= 18.04+updates) or Debian (>= 10):
 ```
@@ -136,9 +136,9 @@
 If not available in the distribution, clang-format-7 can be installed from
 https://releases.llvm.org/download.html or https://apt.llvm.org
 
-To install autopep8 and flake8 on Ubuntu:
+To install autopep8, flake8 and phpcs on Ubuntu:
 ```
-sudo apt-get install python-autopep8 flake8
+sudo apt-get install python-autopep8 flake8 php-codesniffer
 ```