diff --git a/jupyter_collaboration/handlers.py b/jupyter_collaboration/handlers.py
index a4d05e72..46ab8e09 100644
--- a/jupyter_collaboration/handlers.py
+++ b/jupyter_collaboration/handlers.py
@@ -330,14 +330,14 @@ async def _clean_room(self) -> None:
         contains a copy of the document. In addition, we remove the file if there is no rooms
         subscribed to it.
         """
-        async with self._room_lock(self._room_id):
-            assert isinstance(self.room, DocumentRoom)
+        assert isinstance(self.room, DocumentRoom)
 
-            if self._cleanup_delay is None:
-                return
+        if self._cleanup_delay is None:
+            return
 
-            await asyncio.sleep(self._cleanup_delay)
+        await asyncio.sleep(self._cleanup_delay)
 
+        async with self._room_lock(self._room_id):
             # Remove the room from the websocket server
             self.log.info("Deleting Y document from memory: %s", self.room.room_id)
             self._websocket_server.delete_room(room=self.room)
diff --git a/tests/test_documents.py b/tests/test_documents.py
index 20efb8dc..ae43fd8d 100644
--- a/tests/test_documents.py
+++ b/tests/test_documents.py
@@ -59,3 +59,25 @@ async def connect(file_format, file_type, file_path):
         tg.start_soon(connect, file_format, file_type, file_path)
     t1 = time()
     assert t1 - t0 < 0.5
+
+
+async def test_room_sequential_opening(
+    rtc_create_file,
+    rtc_connect_doc_client,
+):
+    file_format = "text"
+    file_type = "file"
+    file_path = "dummy.txt"
+    await rtc_create_file(file_path)
+
+    async def connect(file_format, file_type, file_path):
+        t0 = time()
+        async with await rtc_connect_doc_client(file_format, file_type, file_path) as ws:
+            pass
+        t1 = time()
+        return t1 - t0
+
+    dt = await connect(file_format, file_type, file_path)
+    assert dt < 1
+    dt = await connect(file_format, file_type, file_path)
+    assert dt < 1