diff --git a/libao/libao-async.rkt b/libao/libao-async.rkt
index 9d93591..dfd8712 100644
--- a/libao/libao-async.rkt
+++ b/libao/libao-async.rkt
@@ -115,8 +115,15 @@
                    (let ((w (ao-shm-stopped shm)))
                      (mutex-unlock (ao-shm-mutex shm))
                      w))))
-    (while (eq? (stopped) #f))
-         (sleep 0.01))
+    (letrec ((loop (λ ()
+                     (if (eq? (stopped) #t)
+                         'stopped
+                         (begin
+                           (sleep 0.01)
+                           (loop))))))
+      (loop)
+      'stopped)
+    )
   )
 
 (define (ao_play_async shm at-second buf-size buf)