diff --git a/Justfile b/Justfile
index 1ac146f9..91ac7ae9 100644
--- a/Justfile
+++ b/Justfile
@@ -83,7 +83,8 @@ nix-upgrade:
 [group('nix')]
 fmt:
   # format the nix files in this repo
-  ls **/*.nix | each { |it| nixfmt $it.name }
+  # (use external find so symlinked dirs like the `result` build output are not followed)
+  ^find . -name '*.nix' -not -path './.git/*' | lines | each { |it| nixfmt $it | ignore }
 
 # Show all the auto gc roots in the nix store
 [group('nix')]