diff --git a/activities/models/post.py b/activities/models/post.py
index e9ec76c..e6a0e36 100644
--- a/activities/models/post.py
+++ b/activities/models/post.py
@@ -724,7 +724,10 @@ class Post(StatorModel):
             .select_related("target")
         )
         async for block in blocks:
-            targets.remove(block.target)
+            try:
+                targets.remove(block.target)
+            except KeyError:
+                pass
         # Now dedupe the targets based on shared inboxes (we only keep one per
         # shared inbox)
         deduped_targets = set()