diff --git a/nixos/modules/services/mail/roundcube.nix b/nixos/modules/services/mail/roundcube.nix
index fc655add00e..4639af33b63 100644
--- a/nixos/modules/services/mail/roundcube.nix
+++ b/nixos/modules/services/mail/roundcube.nix
@@ -11,8 +11,8 @@ in
 
     listenAddress = mkOption {
       type = types.str;
-      default = 127.0.0.1;
-      description = "Listening address";
+      default = "[::]";
+      description = "Listening address. IPv6 addresses must be enclosed in square brackets";
     };
 
     listenPort = mkOption {