diff --git a/magnum/common/utils.py b/magnum/common/utils.py
index 834e62f503..7c8910504b 100644
--- a/magnum/common/utils.py
+++ b/magnum/common/utils.py
@@ -354,7 +354,7 @@ def file_open(*args, **kwargs):
 def hash_file(file_like_object):
     """Generate a hash for the contents of a file."""
     checksum = hashlib.sha1()
-    for chunk in iter(lambda: file_like_object.read(32768), b''):
+    for chunk in iter(lambda: six.b(file_like_object.read(32768)), b''):
         checksum.update(chunk)
     return checksum.hexdigest()
 
diff --git a/magnum/tests/unit/common/test_utils.py b/magnum/tests/unit/common/test_utils.py
index ce388cf60a..9fdc8f0c37 100644
--- a/magnum/tests/unit/common/test_utils.py
+++ b/magnum/tests/unit/common/test_utils.py
@@ -336,7 +336,7 @@ class GenericUtilsTestCase(base.TestCase):
         data = 'Mary had a little lamb, its fleece as white as snow'
         flo = six.StringIO(data)
         h1 = utils.hash_file(flo)
-        h2 = hashlib.sha1(data).hexdigest()
+        h2 = hashlib.sha1(six.b(data)).hexdigest()
         self.assertEqual(h1, h2)
 
     def test_is_valid_boolstr(self):