diff --git a/pkgs/os-specific/linux/systemd/default.nix b/pkgs/os-specific/linux/systemd/default.nix
index 3cff6512fe4..b5d37cc9a31 100644
--- a/pkgs/os-specific/linux/systemd/default.nix
+++ b/pkgs/os-specific/linux/systemd/default.nix
@@ -8,6 +8,8 @@
 
 assert stdenv.isLinux;
 
+# FIXME: When updating, please remove makeFlags -- `hwdb_bin` flag is not supported anymore.
+
 stdenv.mkDerivation rec {
   version = "228";
   name = "systemd-${version}";