diff --git a/marginaltool b/marginaltool
index c5b5acc..d62aea9 100755
--- a/marginaltool
+++ b/marginaltool
@@ -34,7 +34,8 @@ def init(args):
             if not args.keyfile or not args.certfile:
                 raise Exception('key or certificate file not specified')
             args.cert = ''.join(
-                cert.split('-----BEGIN CERTIFICATE-----', 1)[1]
+                open(args.certfile).read()
+                    .split('-----BEGIN CERTIFICATE-----', 1)[1]
                     .split('-----END CERTIFICATE-----', 1)[0])
 
         case 'pkcs11':