Fix website url to use https.
diff --git a/library/x509write_crt.c b/library/x509write_crt.c
index c53b235..ee3448e 100644
--- a/library/x509write_crt.c
+++ b/library/x509write_crt.c
@@ -3,7 +3,7 @@
*
* Copyright (C) 2006-2014, ARM Limited, All Rights Reserved
*
- * This file is part of mbed TLS (http://www.polarssl.org)
+ * This file is part of mbed TLS (https://www.polarssl.org)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by