diff --git a/changelog.d/19730.bugfix b/changelog.d/19730.bugfix
new file mode 100644
index 00000000000..074405d9442
--- /dev/null
+++ b/changelog.d/19730.bugfix
@@ -0,0 +1 @@
+Work around bug that sometimes breaks joining restricted rooms that require a remote join. Contributed by @tulir @ Beeper.
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 236c8ca03c7..8a19dba5ee5 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -1355,7 +1355,15 @@ async def _should_perform_remote_join(
         current_state = {
             state_key: event_map[event_id]
             for state_key, event_id in state_before_join.items()
+            # TODO figure out why events present in state_before_join are sometimes not found in event_map
+            #  See https://github.com/element-hq/synapse/issues/19465
+            if event_id in event_map
         }
+        if len(current_state) < len(state_before_join):
+            logger.warning(
+                "Some events from state_before_join were not found in event_map: %s",
+                set(state_before_join.values()) - set(event_map.keys()),
+            )
         servers_that_can_issue_invite = get_servers_from_users(
             get_users_which_can_issue_invite(current_state)
         )