diff --git a/trezor_agent/client.py b/trezor_agent/client.py
index 6a9a4d4..e009f7f 100644
--- a/trezor_agent/client.py
+++ b/trezor_agent/client.py
@@ -67,7 +67,7 @@ class Client(object):
         log.debug('nonce: %s', binascii.hexlify(msg['nonce']))
         log.debug('fingerprint: %s', msg['public_key']['fingerprint'])
         log.debug('hidden challenge size: %d bytes', len(blob))
-        log.debug('visual challenge size: %d bytes', len(visual))
+        log.debug('visual challenge size: %d bytes = %r', len(visual), visual)
 
         log.info('please confirm user "%s" login to "%s" using %s...',
                  msg['user'], label, self.device_name)