diff --git a/pkgs/additional/rtl8723cs-firmware/default.nix b/pkgs/additional/rtl8723cs-firmware/default.nix
index 4431fa256..aab21b2a8 100644
--- a/pkgs/additional/rtl8723cs-firmware/default.nix
+++ b/pkgs/additional/rtl8723cs-firmware/default.nix
@@ -27,6 +27,9 @@ stdenv.mkDerivation {
     # other sources:
     # - <https://megous.com/git/linux-firmware>
     # - <https://github.com/armbian/firmware>
+    #
+    # mobile-nixos used this source until switching to megi's on 2021/07/26:
+    # - <https://github.com/NixOS/mobile-nixos/pull/391/files>
     homepage = "https://github.com/anarsoul/rtl8723bt-firmware";
     license = licenses.unfreeRedistributableFirmware;
     maintainers = with maintainers; [ colinsane ];