diff --git a/nixos/modules/monitoring/exporters/promtail.nix b/nixos/modules/monitoring/exporters/promtail.nix
index def02568e693be99cb1fe94c3e3d15fc81df5c1b..9470cbda74bd9de0f241650c525e77e54e1ef049 100644
--- a/nixos/modules/monitoring/exporters/promtail.nix
+++ b/nixos/modules/monitoring/exporters/promtail.nix
@@ -40,19 +40,16 @@ in {
     # but generally suppose that people will look at Loki instead.
     services.journald.extraConfig = ''
       # This tells journald it can discard log files that contain only log
-      # entries that are older than 29 days.
+      # entries older than...
       MaxRetentionSec=${logRetention}
 
       # This tells journald to start a new log file once a day.  Together with
       # the MaxRetentionSec setting, this means that entries are kept for
-      # between 29 and 30 days (plus whatever scheduling slop journald has in
-      # enforcing these limits).
+      # up to a full day longer than MaxRetentionSec.
       #
       # https://www.freedesktop.org/software/systemd/man/journald.conf.html
       # for further details about these options.
       #
-      # A maximum retention of 30 days conforms to the published log retention
-      # policy.
       MaxFileSec=1day
     '';
 
diff --git a/nixos/modules/monitoring/policy.nix b/nixos/modules/monitoring/policy.nix
index 599d0bb4d58d90517b6b53fdf653aec53e34558e..514f1892bf2e807f8ece98d56bc630154f90bcd6 100644
--- a/nixos/modules/monitoring/policy.nix
+++ b/nixos/modules/monitoring/policy.nix
@@ -1,11 +1,14 @@
 # Codify our log data retention policy
+#
+# A maximum retention of 30 days conforms to the published log retention policy,
+# see https://private.storage/privacy-policy/ .
 
 { options, lib, ... }: {
   options.services.private-storage.monitoring.policy = {
     logRetentionSeconds = lib.mkOption {
       type = lib.types.int;
       description = "How long do we retain logs (seconds)";
-      default = 29 * (24 * 60 * 60);  # 29 days.
+      default = 29 * (24 * 60 * 60);  # 29 days, to accomodate for the journald log rotation (1 day).
     };
   };
 }