diff --git a/dal/views.py b/dal/views.py
index 0d588c1248939a062f51a7efabdc580c67dbcd1c..cd5bb1b19157ec6d55c5109aaed3f2aec21ef7d5 100644
--- a/dal/views.py
+++ b/dal/views.py
@@ -511,6 +511,10 @@ class UserCreateAPI(APIView):
 
         if username == "" or not username:
             return Response('Please supply a username.', 400)
+
+        if not is_username_valid(username):
+            return Response('Username is not valid.', 400)
+
         try:
             validate_email(email)
         except ValidationError: