diff --git a/nixos/modules/services/web-apps/nextcloud.nix b/nixos/modules/services/web-apps/nextcloud.nix
index c7e97bbeba9..d0efdf88d73 100644
--- a/nixos/modules/services/web-apps/nextcloud.nix
+++ b/nixos/modules/services/web-apps/nextcloud.nix
@@ -171,7 +171,12 @@ in {
       dbhost = mkOption {
         type = types.nullOr types.str;
         default = "localhost";
-        description = "Database host.";
+        description = ''
+          Database host.
+
+          Note: for using Unix authentication with PostgreSQL, this should be
+          set to <literal>/tmp</literal>.
+        '';
       };
       dbport = mkOption {
         type = with types; nullOr (either int str);