diff --git a/docs/CONTRIBUTING.md b/docs/CONTRIBUTING.md
index 38dabaec4..a59f58ad7 100644
--- a/docs/CONTRIBUTING.md
+++ b/docs/CONTRIBUTING.md
@@ -200,3 +200,4 @@ Or you can also use the [nix breakpoint hook](https://nixos.org/manual/nixpkgs/s
 
 - Every new module name should be in kebab-case.
 - Every fact definition, where possible should be in kebab-case.
+- Every vars definition, where possible should be in kebab-case.