diff --git a/man2/fanotify_init.2 b/man2/fanotify_init.2
index e54fe7e85..4824378d8 100644
--- a/man2/fanotify_init.2
+++ b/man2/fanotify_init.2
@@ -191,6 +191,13 @@ The number of fanotify groups of the user exceeds 128.
 .B ENOMEM
 The allocation of memory for the notification group failed.
 .TP
+.B ENOSYS
+This kernel does not implement
+.BR fanotify_init ().
+To make the fanotify API available,
+.B CONFIG_FANOTIFY
+has to be enabled in the Linux configuration.
+.TP
 .B EPERM
 The operation is not permitted because the caller lacks the
 .B CAP_SYS_ADMIN