diff --git a/src/param.rs b/src/param.rs
index 3319fcda1..f4d752871 100644
--- a/src/param.rs
+++ b/src/param.rs
@@ -175,7 +175,7 @@ pub enum Param {
     /// For Chats of type [`Chattype::OutBroadcast`] and [`Chattype::InBroadcast`]: // TODO (or just OutBroadcast)
     /// The symmetric key shared among all chat participants,
     /// used to encrypt and decrypt messages.
-    SymmetricKey = b'z', // TODO remove this again
+    SymmetricKey = b'z', // TODO remove this
 
     /// For Contacts: If this is the List-Post address of a mailing list, contains
     /// the List-Id of the mailing list (which is also used as the group id of the chat).
diff --git a/src/receive_imf.rs b/src/receive_imf.rs
index f27fbf7fc..aa1980332 100644
--- a/src/receive_imf.rs
+++ b/src/receive_imf.rs
@@ -44,7 +44,7 @@ use crate::securejoin::{self, handle_securejoin_handshake, observe_securejoin_on
 use crate::simplify;
 use crate::stock_str;
 use crate::sync::Sync::*;
-use crate::tools::{self, buf_compress, remove_subject_prefix};
+use crate::tools::{self, buf_compress, create_broadcast_shared_secret, remove_subject_prefix};
 use crate::{chatlist_events, ensure_and_debug_assert, ensure_and_debug_assert_eq, location};
 use crate::{contact, imap};
 
@@ -1566,7 +1566,8 @@ async fn do_chat_assignment(
                         } else {
                             let name =
                                 compute_mailinglist_name(mailinglist_header, &listid, mime_parser);
-                            chat::create_broadcast_ex(context, Nosync, listid, name).await?
+                            let secret = create_broadcast_shared_secret();
+                            chat::create_broadcast_ex(context, Nosync, listid, name, secret).await?
                         },
                     );
                 }