diff --git a/aio-posix.c b/aio-posix.c
index 88d09e1..fe4dbb4 100644
--- a/aio-posix.c
+++ b/aio-posix.c
@@ -264,5 +264,6 @@ bool aio_poll(AioContext *ctx, bool blocking)
         }
     }
 
-    return progress;
+    assert(progress || busy);
+    return true;
 }
diff --git a/include/block/aio.h b/include/block/aio.h
index 0933f05..8eda924 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -173,16 +173,14 @@ bool aio_pending(AioContext *ctx);
  * aio as a result of executing I/O completion or bh callbacks.
  *
  * If there is no pending AIO operation or completion (bottom half),
- * return false.  If there are pending bottom halves, return true.
+ * return false.  If there are pending AIO operations of bottom halves,
+ * return true.
  *
  * If there are no pending bottom halves, but there are pending AIO
  * operations, it may not be possible to make any progress without
  * blocking.  If @blocking is true, this function will wait until one
  * or more AIO events have completed, to ensure something has moved
  * before returning.
- *
- * If @blocking is false, this function will also return false if the
- * function cannot make any progress without blocking.
  */
 bool aio_poll(AioContext *ctx, bool blocking);
 
diff --git a/tests/test-aio.c b/tests/test-aio.c
index e4ebef7..c173870 100644
--- a/tests/test-aio.c
+++ b/tests/test-aio.c
@@ -315,13 +315,13 @@ static void test_wait_event_notifier_noflush(void)
     event_notifier_set(&data.e);
     g_assert(aio_poll(ctx, false));
     g_assert_cmpint(data.n, ==, 1);
-    g_assert(!aio_poll(ctx, false));
+    g_assert(aio_poll(ctx, false));
     g_assert_cmpint(data.n, ==, 1);
 
     event_notifier_set(&data.e);
     g_assert(aio_poll(ctx, false));
     g_assert_cmpint(data.n, ==, 2);
-    g_assert(!aio_poll(ctx, false));
+    g_assert(aio_poll(ctx, false));
     g_assert_cmpint(data.n, ==, 2);
 
     event_notifier_set(&dummy.e);