diff --git a/acme_tiny.py b/acme_tiny.py
index d992d02d..15e72e72 100755
--- a/acme_tiny.py
+++ b/acme_tiny.py
@@ -189,11 +189,18 @@ def main(argv=None):
     parser.add_argument("--ca", default=DEFAULT_CA, help="DEPRECATED! USE --directory-url INSTEAD!")
     parser.add_argument("--contact", metavar="CONTACT", default=None, nargs="*", help="Contact details (e.g. mailto:aaa@bbb.com) for your account-key")
     parser.add_argument("--check-port", metavar="PORT", default=None, help="what port to use when self-checking the challenge file, default is port 80")
+    parser.add_argument("--outfile", metavar="FILE", required=False, default=None, help="write signed cert to this file. default=STDOUT")
 
     args = parser.parse_args(argv)
     LOGGER.setLevel(args.quiet or LOGGER.level)
     signed_crt = get_crt(args.account_key, args.csr, args.acme_dir, log=LOGGER, CA=args.ca, disable_check=args.disable_check, directory_url=args.directory_url, contact=args.contact, check_port=args.check_port)
-    sys.stdout.write(signed_crt)
+
+    if args.outfile:
+        LOGGER.info("Writing signed certificate to {outfile}".format(outfile=args.outfile))
+        with open(args.outfile, "w") as fout:
+            fout.write(signed_crt)
+    else:
+        sys.stdout.write(signed_crt)
 
 if __name__ == "__main__": # pragma: no cover
     main(sys.argv[1:])