diff --git a/src/modules/client/pages/CourseCheckout.jsx b/src/modules/client/pages/CourseCheckout.jsx
index 1bc6e64..16e908e 100644
--- a/src/modules/client/pages/CourseCheckout.jsx
+++ b/src/modules/client/pages/CourseCheckout.jsx
@@ -75,7 +75,14 @@ export default function CourseCheckout() {
     if (!wasCancelled) return;
     const orderId = searchParams.get("token");
     if (orderId) cancelCourseOrder(orderId);
-    toast("Payment was cancelled.");
+    // Deferred to a new macrotask: this page renders as an <Outlet /> child,
+    // which sits before <Toaster /> in ClientLayout's JSX — so a toast fired
+    // synchronously in this mount-time effect races the Toaster's own mount
+    // effect (which subscribes to sonner's store) and is silently dropped,
+    // since sonner only notifies subscribers already listening at publish
+    // time (no replay for late subscribers). setTimeout(0) pushes the call
+    // past the current effect-flush, after Toaster has subscribed.
+    setTimeout(() => toast("Payment was cancelled."), 0);
     navigate(`/course/${courseId}/checkout`, { replace: true });
   }, [wasCancelled]); // eslint-disable-line react-hooks/exhaustive-deps