Update fsnotify_open_bsd.go
diff --git a/fsnotify_open_bsd.go b/fsnotify_open_bsd.go
index 37ea998..f728a6f 100644
--- a/fsnotify_open_bsd.go
+++ b/fsnotify_open_bsd.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build freebsd openbsd netbsd
+// +build freebsd openbsd netbsd dragonfly
 
 package fsnotify