diff --git a/codex-rs/utils/pty/src/lib.rs b/codex-rs/utils/pty/src/lib.rs
index cd98107ca..38e86bd2a 100644
--- a/codex-rs/utils/pty/src/lib.rs
+++ b/codex-rs/utils/pty/src/lib.rs
@@ -54,6 +54,7 @@ impl ExecCommandSession {
     pub fn new(
         writer_tx: mpsc::Sender<Vec<u8>>,
         output_tx: broadcast::Sender<Vec<u8>>,
+        initial_output_rx: broadcast::Receiver<Vec<u8>>,
         killer: Box<dyn portable_pty::ChildKiller + Send + Sync>,
         reader_handle: JoinHandle<()>,
         writer_handle: JoinHandle<()>,
@@ -62,7 +63,6 @@ impl ExecCommandSession {
         exit_code: Arc<StdMutex<Option<i32>>>,
         pair: PtyPairWrapper,
     ) -> (Self, broadcast::Receiver<Vec<u8>>) {
-        let initial_output_rx = output_tx.subscribe();
         (
             Self {
                 writer_tx,
@@ -177,6 +177,8 @@ pub async fn spawn_pty_process(
 
     let (writer_tx, mut writer_rx) = mpsc::channel::<Vec<u8>>(128);
     let (output_tx, _) = broadcast::channel::<Vec<u8>>(256);
+    // Subscribe before starting the reader thread.
+    let initial_output_rx = output_tx.subscribe();
 
     let mut reader = pair.master.try_clone_reader()?;
     let output_tx_clone = output_tx.clone();
@@ -242,6 +244,7 @@ pub async fn spawn_pty_process(
     let (session, output_rx) = ExecCommandSession::new(
         writer_tx,
         output_tx,
+        initial_output_rx,
         killer,
         reader_handle,
         writer_handle,