diff --git a/man3/aio_return.3 b/man3/aio_return.3
index 3e6f334e7..37d735ce9 100644
--- a/man3/aio_return.3
+++ b/man3/aio_return.3
@@ -55,6 +55,7 @@ the value that would have been returned in case of a synchronous
 or
 .BR fdatasync (2),
 call.
+On error, \-1 is returned, and \fIerrno\fP is set appropriately.
 
 If the asynchronous I/O operation has not yet completed,
 the return value and effect of