diff --git a/gNMI_Subscribe.py b/gNMI_Subscribe.py
index cae533b..d7781e5 100644
--- a/gNMI_Subscribe.py
+++ b/gNMI_Subscribe.py
@@ -208,7 +208,7 @@ def gen_request( opt ):
     if options.tls or options.cert:
         log.debug("Create SSL Channel")
         if options.cert:
-            cred = grpc.ssl_channel_credentials(root_certificates=open(options.cert).read())
+            cred = grpc.ssl_channel_credentials(root_certificates=open(options.cert).read().encode("us-ascii"))
             opts = []
             if options.altName:
                 opts.append(('grpc.ssl_target_name_override', options.altName,))