diff --git a/modules/nixos/system/persist/default.nix b/modules/nixos/system/persist/default.nix
index ac1820e..2e7bb07 100644
--- a/modules/nixos/system/persist/default.nix
+++ b/modules/nixos/system/persist/default.nix
@@ -47,18 +47,17 @@ in
   config = lib.mkIf cfg.enable {
     environment.persistence."${cfg.mountPoint}" = {
       files = [
-        "/etc/machine-id"
-        "/etc/adjtime"
-        "/var/lib/systemd/timesync/clock"
+        "/etc/machine-id" # Machine-specific ID
+        "/etc/adjtime" # Clock drift factor and offsets
       ]
       ++ lib.unique cfg.files
       ;
 
       directories = [
         "/etc/nixos" # In case it's storage directory of our configuration
-        "/var/log"
+        "/var/log" # Logs
         "/var/lib/nixos" # UID/GID maps
-        "/var/lib/systemd/coredump"
+        "/var/lib/systemd/coredump" # Coredumps
 
         "/var/lib/systemd" # FIXME: needed?
         "/var/spool" # FIXME: needed?