diff --git a/pkgs/development/libraries/haskell/managed/default.nix b/pkgs/development/libraries/haskell/managed/default.nix
index 5827038627c..febb1f8c574 100644
--- a/pkgs/development/libraries/haskell/managed/default.nix
+++ b/pkgs/development/libraries/haskell/managed/default.nix
@@ -1,3 +1,5 @@
+# This file was auto-generated by cabal2nix. Please do NOT edit manually!
+
 { cabal, transformers }:
 
 cabal.mkDerivation (self: {