diff --git a/nixos/modules/config/zram.nix b/nixos/modules/config/zram.nix
index 44db5ce9d641..15f626c3f09c 100644
--- a/nixos/modules/config/zram.nix
+++ b/nixos/modules/config/zram.nix
@@ -63,7 +63,8 @@ in
         type = with lib.types; nullOr int;
         description = ''
           Maximum total amount of memory (in bytes) that can be stored in the zram
-          swap devices.
+          swap devices. If set, the smaller one of this option and memoryPercent would
+          be used.
           This doesn't define how much memory will be used by the zram swap devices.
         '';
       };