diff --git a/django/http/__init__.py b/django/http/__init__.py
index 942b022816..c662f5f0a9 100644
--- a/django/http/__init__.py
+++ b/django/http/__init__.py
@@ -227,7 +227,7 @@ class HttpResponse(object):
     def tell(self):
         if not self._is_string:
             raise Exception, "This %s instance cannot tell its position" % self.__class__
-        return sum(len(chunk) for chunk in self.iterator)
+        return sum([len(chunk) for chunk in self.iterator])
 
 class HttpResponseRedirect(HttpResponse):
     def __init__(self, redirect_to):