1 files changed, 1 insertions, 1 deletions

diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py

index 3aa610c85c..d64119a473 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -398,7 +398,7 @@ class SQLBaseStore(object):
 
                 if del_evs:
                     prune_event(ev)
-                    ev.pruned = del_evs[0]
+                    ev.pruned_because = del_evs[0]
 
         return events