diff --git a/src/pinned-pkgs.nix b/src/pinned-pkgs.nix
index 048fa5a..f7e72c8 100644
--- a/src/pinned-pkgs.nix
+++ b/src/pinned-pkgs.nix
@@ -1,6 +1,7 @@
 { fetchFromGitHub, arch }:
 
 let
+  # head of nixos-19.03 as of 2019-09-15
   pinnedPkgs = fetchFromGitHub {
     owner = "NixOS";
     repo = "nixpkgs";