diff --git a/man/io_uring_get_sqe.3 b/man/io_uring_get_sqe.3
index 58c8b96f..ce446142 100644
--- a/man/io_uring_get_sqe.3
+++ b/man/io_uring_get_sqe.3
@@ -32,10 +32,24 @@ prep functions such as
 and submitted via
 .BR io_uring_submit (3).
 
+Note that the prep functions don't set the
+.B user_data
+field of the SQE, that is left to the caller. If the caller expects
+.BR io_uring_cqe_get_data (3)
+or
+.BR io_uring_cqe_get_data64 (3)
+to return valid data when reaping IO completions, either
+.BR io_uring_sqe_set_data (3)
+or
+.BR io_uring_sqe_set_data64 (3)
+.B MUST
+have been called submitting the request.
+
 .SH RETURN VALUE
 .BR io_uring_get_sqe (3)
 returns a pointer to the next submission queue event on success and NULL on
 failure. If NULL is returned, the SQ ring is currently full and entries must
 be submitted for processing before new ones can get allocated.
 .SH SEE ALSO
-.BR io_uring_submit (3)
+.BR io_uring_submit (3),
+.BR io_uring_sqe_set_data (3)