diff --git a/man2/tee.2 b/man2/tee.2
index 7bb0d3a31..03d043b46 100644
--- a/man2/tee.2
+++ b/man2/tee.2
@@ -100,7 +100,9 @@ is set to indicate the error.
 .B EAGAIN
 .B SPLICE_F_NONBLOCK
 was specified in
-.IR flags ,
+.IR flags
+or one of the file descriptors had been marked as nonblocking
+.RB ( O_NONBLOCK ) ,
 and the operation would block.
 .TP
 .B EINVAL