diff --git a/.github/workflows/repo-list.yml b/.github/workflows/repo-list.yml
index 3bf4d9b..eea77e1 100644
--- a/.github/workflows/repo-list.yml
+++ b/.github/workflows/repo-list.yml
@@ -14,7 +14,7 @@ jobs:
       - name: setup
         id: setup
         run: |
-          echo "title=devdoc: update repo list $(date -u +"%Y-%m-%d")" >> $GITHUB_OUTPUT
+          echo "title=devdoc: update repo list $(date -u +"%Y-%m-%d")" >> "$GITHUB_OUTPUT"
           git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
           git config user.name "github-actions[bot]"
       - name: Update repo list
diff --git a/dev/treefmt.nix b/dev/treefmt.nix
index 541e327..3c1fcae 100644
--- a/dev/treefmt.nix
+++ b/dev/treefmt.nix
@@ -7,6 +7,11 @@
   programs.prettier.enable = true;
 
   settings.formatter = {
+    actionlint = {
+      command = pkgs.actionlint;
+      includes = [ ".github/workflows/*.yml" ];
+    };
+
     nix = {
       command = "sh";
       options = [