diff --git a/modules/lang/nix/doctor.el b/modules/lang/nix/doctor.el
new file mode 100644
index 000000000..440ef31b0
--- /dev/null
+++ b/modules/lang/nix/doctor.el
@@ -0,0 +1,6 @@
+;; -*- lexical-binding: t; no-byte-compile: t; -*-
+;;; lang/nix/doctor.el
+
+(unless (executable-find "nixfmt")
+  (warn! "Couldn't find nixfmt. nix-format-buffer won't work"))
+