diff --git a/src/backend/matrix_client.py b/src/backend/matrix_client.py
index df25aa4c..98779ee6 100644
--- a/src/backend/matrix_client.py
+++ b/src/backend/matrix_client.py
@@ -75,6 +75,12 @@ REPLY_FALLBACK = (
 )
 
 
+class SyncFilterIds(NamedTuple):
+    """Uploaded filter IDs for various API."""
+
+    first:  str
+    others: str
+
 class UploadReturn(NamedTuple):
     """Details for an uploaded file."""
 
@@ -185,10 +191,12 @@ class MatrixClient(nio.AsyncClient):
         self.upload_tasks:       Dict[UUID, asyncio.Task]        = {}
         self.send_message_tasks: Dict[UUID, asyncio.Task]        = {}
 
-        self._presence:       str                 = ""
-        self.first_sync_done: asyncio.Event       = asyncio.Event()
-        self.first_sync_date: Optional[datetime]  = None
-        self.last_sync_error: Optional[Exception] = None
+        self._presence:             str                     = ""
+        self._sync_filter_ids:      Optional[SyncFilterIds] = None
+        self._sync_filter_ids_lock: asyncio.Lock            = asyncio.Lock()
+        self.first_sync_done:       asyncio.Event           = asyncio.Event()
+        self.first_sync_date:       Optional[datetime]      = None
+        self.last_sync_error:       Optional[Exception]     = None
 
         self.past_tokens:          Dict[str, str] = {}     # {room_id: token}
         self.fully_loaded_rooms:   Set[str]       = set()  # {room_id}
@@ -370,25 +378,17 @@ class MatrixClient(nio.AsyncClient):
         )
         self.server_config_task.add_done_callback(on_server_config_response)
 
-        filter1 = deepcopy(self.lazy_load_filter)
-        utils.dict_update_recursive(filter1, self.low_limit_filter)
-
-        cfg = self.backend.ui_settings
-
-        if cfg["hideUnknownEvents"]:
-            filter1["room"]["timeline"]["not_types"].extend(
-                self.no_unknown_events_filter["room"]["timeline"]["not_types"],
-            )
-
         await self.auto_verify_all_other_accounts()
 
         while True:
             try:
+                sync_filter_ids = await self.sync_filter_ids()
+
                 self.sync_task = asyncio.ensure_future(self.sync_forever(
                     timeout           = 10_000,
                     loop_sleep_time   = 1000,
-                    sync_filter       = self.lazy_load_filter,
-                    first_sync_filter = filter1,
+                    first_sync_filter = sync_filter_ids.first,
+                    sync_filter       = sync_filter_ids.others,
                 ))
                 await self.sync_task
                 break  # task cancelled
@@ -454,6 +454,35 @@ class MatrixClient(nio.AsyncClient):
         return (await self.content_repository_config()).upload_size
 
 
+    async def sync_filter_ids(self) -> SyncFilterIds:
+        """Return our sync/messages filter IDs, upload them if needed."""
+
+        async with self._sync_filter_ids_lock:
+            if self._sync_filter_ids:
+                return self._sync_filter_ids
+
+            others = deepcopy(self.lazy_load_filter)
+            first  = deepcopy(others)
+
+            utils.dict_update_recursive(first, self.low_limit_filter)
+
+            if self.backend.ui_settings["hideUnknownEvents"]:
+                first["room"]["timeline"]["not_types"].extend(
+                    self.no_unknown_events_filter
+                    ["room"]["timeline"]["not_types"],
+                )
+
+            others_id = (await self.upload_filter(**others)).filter_id
+            first_id  = others_id
+
+            if others != first:
+                resp     = await self.upload_filter(**first)
+                first_id = resp.filter_id
+
+            self._sync_filter_ids = SyncFilterIds(others_id, first_id)
+            return self._sync_filter_ids
+
+
     async def pause_while_offline(self) -> None:
         """Block until our account is online."""
         while (