diff --git a/reviewboard/extensions/templatetags/rb_extensions.py b/reviewboard/extensions/templatetags/rb_extensions.py
index cc1f99747f9a68f5bce7b161f07f4b8bbc5644e7..f49f9cc4312732757f516e6ac4166b9cfd7e3de0 100644
--- a/reviewboard/extensions/templatetags/rb_extensions.py
+++ b/reviewboard/extensions/templatetags/rb_extensions.py
@@ -30,7 +30,7 @@ def action_hooks(context, hook_cls, action_key="action",
                     try:
                         html.append(render_to_string(
                             template_name=template_name,
-                            context=context))
+                            context=context.flatten()))
                     except Exception as e:
                         logger.error(
                             'Error when rendering template for action "%s" '
@@ -66,7 +66,7 @@ def navigation_bar_hooks(context):
                     context['entry'] = nav_info
                     html.append(render_to_string(
                         template_name='extensions/navbar_entry.html',
-                        context=context))
+                        context=context.flatten()))
                     context.pop()
         except Exception as e:
             extension = hook.extension
diff --git a/reviewboard/reviews/actions.py b/reviewboard/reviews/actions.py
index a3cc69862b1cb089cc7d76299a484a1910b5c57a..75ea54ccd4fa3ef97f9e9c077aab01ab812f4bf8 100644
--- a/reviewboard/reviews/actions.py
+++ b/reviewboard/reviews/actions.py
@@ -187,7 +187,7 @@ class BaseReviewRequestAction(object):
 
             try:
                 context[action_key] = self.copy_to_dict(context)
-                content = render_to_string(template_name, context)
+                content = render_to_string(template_name, context.flatten())
             finally:
                 context.pop()
 
diff --git a/reviewboard/reviews/templatetags/reviewtags.py b/reviewboard/reviews/templatetags/reviewtags.py
index 215263173bae2265f7fcdcd0b342ddc58a45f93f..334f01d7069878c2280ef80c2953afd623d63d80 100644
--- a/reviewboard/reviews/templatetags/reviewtags.py
+++ b/reviewboard/reviews/templatetags/reviewtags.py
@@ -1,7 +1,6 @@
 import logging
 
-from django import template
-from django.template import TemplateSyntaxError
+from django.template import Library, TemplateSyntaxError
 from django.template.defaultfilters import escapejs, stringfilter
 from django.template.loader import render_to_string
 from django.utils.html import format_html
@@ -35,7 +34,7 @@ from reviewboard.site.urlresolvers import local_site_reverse
 logger = logging.getLogger(__name__)
 
 
-register = template.Library()
+register = Library()
 
 
 @register.simple_tag(takes_context=True)
@@ -146,7 +145,7 @@ def _generate_reply_html(context, user, context_id, review, reply, timestamp,
     try:
         return render_to_string(
             template_name='reviews/review_reply.html',
-            context=context)
+            context=context.flatten())
     finally:
         context.pop()
 
@@ -615,7 +614,7 @@ def render_star(user, obj):
         else:
             starred = profile.starred_groups.filter(pk=obj.id).exists()
     else:
-        raise template.TemplateSyntaxError(
+        raise TemplateSyntaxError(
             "star tag received an incompatible object type (%s)" %
             type(obj))