diff --git a/pybtc/functions/bip39_mnemonic.py b/pybtc/functions/bip39_mnemonic.py
index e4a4c71..6a4303d 100644
--- a/pybtc/functions/bip39_mnemonic.py
+++ b/pybtc/functions/bip39_mnemonic.py
@@ -83,7 +83,9 @@ def entropy_to_mnemonic(entropy, language='english', word_list_dir=None, word_li
     i = int.from_bytes(entropy, byteorder="big")
     # append checksum
     i = (i << len(entropy) * 8 // 32) | sha256(entropy)[0]
-    return " ".join([word_list[i.__rshift__(((d - 1) * 11)) & 2047] for d in range(int(i.bit_length() // 11), 0, -1)])
+
+    return " ".join([word_list[i.__rshift__(((d - 1) * 11)) & 2047]
+                     for d in range(int((len(entropy) * 8 + 8) // 11), 0, -1)])
 
 
 def mnemonic_to_entropy(mnemonic, language='english', word_list_dir=None,
diff --git a/pybtc/test/mnemonic.py b/pybtc/test/mnemonic.py
index b8272a3..3c98e97 100644
--- a/pybtc/test/mnemonic.py
+++ b/pybtc/test/mnemonic.py
@@ -33,3 +33,7 @@ class BlockDeserializeTests(unittest.TestCase):
         self.assertEqual(private_from_xprivate_key(xpriv), "L2VnL3zxnNE1jRSemyP7U6PvWuNLvuV5iMJdc2RJGALjZ6HYik7y")
         self.assertEqual(public_from_xpublic_key(xpub),
                          private_to_public_key("L2VnL3zxnNE1jRSemyP7U6PvWuNLvuV5iMJdc2RJGALjZ6HYik7y"))
+        for i in range(100):
+            e = generate_entropy()
+            m = entropy_to_mnemonic(e)
+            self.assertEqual(e, mnemonic_to_entropy(m))
diff --git a/setup.py b/setup.py
index 690ffc7..0951ac0 100644
--- a/setup.py
+++ b/setup.py
@@ -5,7 +5,7 @@ from setuptools import setup, find_packages
 
 
 setup(name='pybtc',
-      version='2.0.2',
+      version='2.0.3',
       description='Python Bitcoin library',
       keywords='bitcoin',
       url='https://github.com/bitaps-com/pybtc',