diff --git a/.github/workflows/check-nix-format.yml b/.github/workflows/check-nix-format.yml
index 87fe5d5464f0..1d51c973be93 100644
--- a/.github/workflows/check-nix-format.yml
+++ b/.github/workflows/check-nix-format.yml
@@ -39,6 +39,10 @@ jobs:
             pkgs/development/cuda-modules
             pkgs/test/cuda
             pkgs/top-level/cuda-packages.nix
+          NIX_FMT_PATHS_K3S: |
+            nixos/modules/services/cluster/k3s
+            nixos/tests/k3s
+            pkgs/applications/networking/cluster/k3s
           NIX_FMT_PATHS_VSCODE_EXTS: pkgs/applications/editors/vscode/extensions
           NIX_FMT_PATHS_PHP_PACKAGES: pkgs/development/php-packages
           NIX_FMT_PATHS_BUILD_SUPPORT_PHP: pkgs/build-support/php