diff --git a/boards/models.py b/boards/models.py
--- a/boards/models.py
+++ b/boards/models.py
@@ -65,7 +65,7 @@ class PostManager(models.Manager):
             thread.last_edit_time = timezone.now()
             thread.save()
 
-            cache_key = thread.get_cache_key
+            cache_key = thread.get_cache_key()
             cache.delete(cache_key)
 
         else: