diff --git a/nixos/modules/services/mail/dovecot.nix b/nixos/modules/services/mail/dovecot.nix
index 7d4a75baa51a..fca57133ebce 100644
--- a/nixos/modules/services/mail/dovecot.nix
+++ b/nixos/modules/services/mail/dovecot.nix
@@ -113,7 +113,7 @@ let
   mailboxes = { lib, pkgs, ... }: {
     options = {
       name = mkOption {
-        type = types.str;
+        type = types.strMatching ''[^"]+'';
         example = "Spam";
         description = "The name of the mailbox.";
       };