diff --git a/lib/mnemonic.py b/lib/mnemonic.py
index 7c2da5387..0aa766bba 100644
--- a/lib/mnemonic.py
+++ b/lib/mnemonic.py
@@ -99,7 +99,8 @@ class Mnemonic(object):
     # Seed derivation no longer follows BIP39
     # Mnemonic phrase uses a hash based checksum, instead of a wordlist-dependent checksum
 
-    def __init__(self, lang='en'):
+    def __init__(self, lang=None):
+        if lang is None: lang='en'
         filename = filenames.get(lang[0:2], 'english.txt')
         path = os.path.join(util.data_dir(), 'wordlist', filename)
         s = open(path,'r').read().strip()