diff --git a/util/validation.py b/util/validation.py
index bbe02e017..895767d98 100644
--- a/util/validation.py
+++ b/util/validation.py
@@ -1,5 +1,4 @@
 import re
-import urllib
 
 INVALID_PASSWORD_MESSAGE = 'Invalid password, password must be at least ' + \
                            '8 characters and contain no whitespace.'
@@ -12,9 +11,9 @@ def validate_email(email_address):
 
 def validate_username(username):
   # Minimum length of 2, maximum length of 255, no url unsafe characters
-  return (urllib.quote(username, safe='') == username and
-          len(username) > 1 and
-          len(username) < 256)
+  return (re.search(r'[^a-z0-9_]', username) is None and
+          len(username) >= 4 and
+          len(username) <= 30)
 
 
 def validate_password(password):