diff --git a/crypto/compat/freezero.c b/crypto/compat/freezero.c
index 8becc00..31face3 100644
--- a/crypto/compat/freezero.c
+++ b/crypto/compat/freezero.c
@@ -1,3 +1,22 @@
+/*
+ * Copyright (c) 2008, 2010, 2011, 2016 Otto Moerbeek <otto@drijf.net>
+ * Copyright (c) 2012 Matthew Dempsky <matthew@openbsd.org>
+ * Copyright (c) 2008 Damien Miller <djm@openbsd.org>
+ * Copyright (c) 2000 Poul-Henning Kamp <phk@FreeBSD.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
 #include <string.h>
 #include <stdlib.h>