diff --git a/selfprivacy-module.nix b/selfprivacy-module.nix
index ec9185c..df92be0 100644
--- a/selfprivacy-module.nix
+++ b/selfprivacy-module.nix
@@ -203,7 +203,7 @@ with lib;
               };
 
               systemdTargets = mkOption {
-                type = with types; listOf strMatching "[a-zA-Z0-9@%:_.\-]+[.](service|socket|device|mount|automount|swap|target|path|timer|scope|slice)";
+                type = with types; listOf (strMatching "[a-zA-Z0-9@%:_.\-]+[.](service|socket|device|mount|automount|swap|target|path|timer|scope|slice)");
                 default = [];
                 example = [ "generate-mastodon-email-password.service" ];
                 description = "Systemd target which generates password file.";