diff --git a/man2/sendfile.2 b/man2/sendfile.2
index 50221eb67..9e6ae3c0b 100644
--- a/man2/sendfile.2
+++ b/man2/sendfile.2
@@ -132,6 +132,14 @@ Descriptor is not valid or locked, or an
 operation is not available for
 .IR in_fd .
 .TP
+.B EINVAL
+.I out_fd
+was has the
+.B O_APPEND
+flag set.
+This is not currently supported by
+.BR sendfile ().
+.TP
 .B EIO
 Unspecified error while reading from
 .IR in_fd .