diff --git a/src/runtime2/scheduler.rs b/src/runtime2/scheduler.rs
index eb8ccbae8bcebfe6e4c6279c845c0c23e0065445..092b65f090107f47fe0c48f9656a99c6f473e2e6 100644
--- a/src/runtime2/scheduler.rs
+++ b/src/runtime2/scheduler.rs
@@ -296,8 +296,9 @@ impl Scheduler {
             if scheduled.ctx.is_in_sync {
                 // Just entered sync region
             } else {
-                // Just left sync region. So clear inbox
-                scheduled.ctx.inbox_messages.clear();
+                // Just left sync region. So clear inbox up until the last
+                // message that was read.
+                scheduled.ctx.inbox_messages.drain(0..scheduled.ctx.inbox_len_read);
                 scheduled.ctx.inbox_len_read = 0;
             }
 
@@ -380,7 +381,7 @@ pub(crate) struct ComponentCtx {
     // Mostly managed by the scheduler
     pub(crate) id: ConnectorId,
     ports: Vec<Port>,
-    inbox_messages: Vec<Message>, // never control or ping messages
+    inbox_messages: Vec<Message>,
     inbox_len_read: usize,
     // Submitted by the component
     is_in_sync: bool,