diff --git a/libdino/src/service/muc_manager.vala b/libdino/src/service/muc_manager.vala
index 4505e992..e8390cdf 100644
--- a/libdino/src/service/muc_manager.vala
+++ b/libdino/src/service/muc_manager.vala
@@ -669,7 +669,10 @@ public class MucManager : StreamInteractionModule, Object {
                 if (m != null) {
                     // For own messages from this device (msg is a duplicate)
                     m.marked = Message.Marked.RECEIVED;
-                    m.server_id = Xep.UniqueStableStanzaIDs.get_stanza_id(stanza, m.counterpart.bare_jid);
+                    string? server_id = Xep.UniqueStableStanzaIDs.get_stanza_id(stanza, m.counterpart.bare_jid);
+                    if (server_id != null) {
+                        m.server_id = server_id;
+                    }
                 }
                 // For own messages from other devices (msg is not a duplicate msg)
                 message.marked = Message.Marked.RECEIVED;