diff --git a/man2/unlink.2 b/man2/unlink.2
index 65a8bcfe0..391cad248 100644
--- a/man2/unlink.2
+++ b/man2/unlink.2
@@ -233,6 +233,11 @@ the process is not privileged (Linux: does not have the
 .B CAP_FOWNER
 capability).
 .TP
+.B EPERM
+The file to be unlinked is marked immutable or append-only.
+(See
+.BR ioctl_iflags (2).)
+.TP
 .B EROFS
 .I pathname
 refers to a file on a read-only filesystem.