Update date in copyright line
diff --git a/programs/pkey/pk_sign.c b/programs/pkey/pk_sign.c
index df60ee5..9efa897 100644
--- a/programs/pkey/pk_sign.c
+++ b/programs/pkey/pk_sign.c
@@ -1,7 +1,7 @@
 /*
  *  Public key-based signature creation program
  *
- *  Copyright (C) 2006-2013, ARM Limited, All Rights Reserved
+ *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
  *
  *  This file is part of mbed TLS (https://tls.mbed.org)
  *