diff --git a/melib/src/mailbox/thread.rs b/melib/src/mailbox/thread.rs
index 1eb87661e..c2b8d5fa5 100644
--- a/melib/src/mailbox/thread.rs
+++ b/melib/src/mailbox/thread.rs
@@ -973,7 +973,7 @@ impl Threads {
                 node_build(tree, id, &mut self.thread_nodes, 1, collection);
                 return;
             }
-            unreachable!();
+            tree.push(ThreadTree::new(id));
         }
 
         /* Trace path back to root ThreadNode */