diff --git a/tos/signal_handlers.py b/tos/signal_handlers.py
index c29398c..800a0a5 100644
--- a/tos/signal_handlers.py
+++ b/tos/signal_handlers.py
@@ -6,7 +6,7 @@ from django.core.cache import caches
 cache = caches[getattr(settings, 'TOS_CACHE_NAME', 'default')]
 
 
-def invalidate_cached_agreements(TermsOfService, instance, **kwargs):
+def invalidate_cached_agreements(sender, **kwargs):
     if kwargs.get('raw', False):
         return