diff --git a/wagtail/wagtailadmin/templatetags/gravatar.py b/wagtail/wagtailadmin/templatetags/gravatar.py
index 908b48395..6ad8a970a 100644
--- a/wagtail/wagtailadmin/templatetags/gravatar.py
+++ b/wagtail/wagtailadmin/templatetags/gravatar.py
@@ -10,7 +10,6 @@
 import hashlib
 
 from django import template
-from django.utils.six import b
 from django.utils.six.moves.urllib.parse import urlencode
 
 register = template.Library()
@@ -28,13 +27,14 @@ class GravatarUrlNode(template.Node):
             return ''
 
         default = "blank"
-        size = int(self.size) * 2 # requested at retina size by default and scaled down at point of use with css
+        size = int(self.size) * 2  # requested at retina size by default and scaled down at point of use with css
 
         gravatar_url = "//www.gravatar.com/avatar/" + hashlib.md5(email.lower().encode('utf-8')).hexdigest() + "?"
         gravatar_url += urlencode({'s': str(size), 'd': default})
 
         return gravatar_url
 
+
 @register.tag
 def gravatar_url(parser, token):
     bits = token.split_contents()