diff --git a/man2/fcntl.2 b/man2/fcntl.2
index 76ca089e1..f9391d33d 100644
--- a/man2/fcntl.2
+++ b/man2/fcntl.2
@@ -424,6 +424,8 @@ instead.
 are used to acquire, release, and test open file description record locks.
 These are advisory byte-range locks whose operation is in most respects
 identical to the traditional record locks described above.
+Open file description locks are Linux-specific,
+and available since Linux 3.15.
 
 The principal difference between the two lock types
 is that whereas traditional record locks