diff --git a/carton/templatetags/carton_tags.py b/carton/templatetags/carton_tags.py
index 397aa8c..1992eee 100644
--- a/carton/templatetags/carton_tags.py
+++ b/carton/templatetags/carton_tags.py
@@ -6,7 +6,6 @@
 
 register = template.Library()
 
-
 def get_cart(context, session_key=None, cart_class=Cart):
     """
     Make the cart object available in template.
@@ -22,4 +21,8 @@ def get_cart(context, session_key=None, cart_class=Cart):
     request = context['request']
     return cart_class(request.session, session_key=session_key)
 
-register.assignment_tag(takes_context=True, name=CART_TEMPLATE_TAG_NAME)(get_cart)
+try:
+    register.simple_tag(takes_context=True, name=CART_TEMPLATE_TAG_NAME)(get_cart)
+except:
+    register.assignment_tag(takes_context=True, name=CART_TEMPLATE_TAG_NAME)(get_cart)
+