diff --git a/pkgs/by-name/xo/xorg-server/package.nix b/pkgs/by-name/xo/xorg-server/package.nix
index e1c04838b820..5c63319bb74e 100644
--- a/pkgs/by-name/xo/xorg-server/package.nix
+++ b/pkgs/by-name/xo/xorg-server/package.nix
@@ -57,6 +57,9 @@
 }:
 stdenv.mkDerivation (finalAttrs: {
   pname = "xorg-server";
+  # `xvfb` inherits `version` and `src` from here, leading to many rebuilds. If
+  # necessary, these can be moved out of lockstep in order to merge updates
+  # quickly.
   version = "21.1.22";
 
   outputs = [