diff --git a/tests/test_ystore.py b/tests/test_ystore.py
index bdd208f..a669d47 100644
--- a/tests/test_ystore.py
+++ b/tests/test_ystore.py
@@ -17,7 +17,7 @@ def __init__(self):
 
     def __call__(self):
         future = asyncio.Future()
-        future.set_result(bytes(self.i))
+        future.set_result(str(self.i).encode())
         self.i += 1
         return future
 
@@ -52,16 +52,18 @@ async def test_ystore(YStore):
     elif YStore == MySQLiteYStore:
         assert Path(MySQLiteYStore.db_path).exists()
     i = 0
-    async for d, m in ystore.read():
+    async for d, m, t in ystore.read():
         assert d == data[i]  # data
-        assert m == bytes(i)  # metadata
+        assert m == str(i).encode()  # metadata
         i += 1
 
+    assert i == len(data)
+
 
 @pytest.mark.asyncio
 async def test_document_ttl_sqlite_ystore(test_ydoc):
     store_name = "my_store"
-    ystore = MySQLiteYStore(store_name, metadata_callback=MetadataCallback(), delete_db=True)
+    ystore = MySQLiteYStore(store_name, delete_db=True)
     now = time.time()
 
     for i in range(3):
@@ -89,7 +91,7 @@ async def test_version(YStore, caplog):
     store_name = "my_store"
     prev_version = YStore.version
     YStore.version = -1
-    ystore = YStore(store_name, metadata_callback=MetadataCallback())
+    ystore = YStore(store_name)
     await ystore.write(b"foo")
     YStore.version = prev_version
     assert "YStore version mismatch" in caplog.text
diff --git a/ypy_websocket/ystore.py b/ypy_websocket/ystore.py
index 793bd8e..374f534 100644
--- a/ypy_websocket/ystore.py
+++ b/ypy_websocket/ystore.py
@@ -1,5 +1,6 @@
 import asyncio
 import logging
+import struct
 import tempfile
 import time
 from abc import ABC, abstractmethod
@@ -21,7 +22,7 @@ class YDocNotFound(Exception):
 class BaseYStore(ABC):
 
     metadata_callback: Optional[Callable] = None
-    version = 1
+    version = 2
 
     @abstractmethod
     def __init__(self, path: str, metadata_callback=None):
@@ -44,7 +45,7 @@ async def encode_state_as_update(self, ydoc: Y.YDoc):
         await self.write(update)
 
     async def apply_updates(self, ydoc: Y.YDoc):
-        async for update, metadata in self.read():  # type: ignore
+        async for update, *rest in self.read():  # type: ignore
             Y.apply_update(ydoc, update)  # type: ignore
 
 
@@ -90,7 +91,7 @@ async def check_version(self) -> int:
                 offset = len(version_bytes)
         return offset
 
-    async def read(self) -> AsyncIterator[Tuple[bytes, bytes]]:  # type: ignore
+    async def read(self) -> AsyncIterator[Tuple[bytes, bytes, float]]:  # type: ignore
         async with self.lock:
             if not await aiofiles.os.path.exists(self.path):
                 raise YDocNotFound
@@ -100,15 +101,16 @@ async def read(self) -> AsyncIterator[Tuple[bytes, bytes]]:  # type: ignore
                 data = await f.read()
                 if not data:
                     raise YDocNotFound
-        is_data = True
-        assert data is not None
+        i = 0
         for d in Decoder(data).read_messages():
-            if is_data:
+            if i == 0:
                 update = d
+            elif i == 1:
+                metadata = d
             else:
-                # yield data and metadata
-                yield update, d
-            is_data = not is_data
+                timestamp = struct.unpack("<d", d)[0]
+                yield update, metadata, timestamp
+            i = (i + 1) % 3
 
     async def write(self, data: bytes) -> None:
         parent = Path(self.path).parent
@@ -121,6 +123,9 @@ async def write(self, data: bytes) -> None:
                 metadata = await self.get_metadata()
                 metadata_len = write_var_uint(len(metadata))
                 await f.write(metadata_len + metadata)
+                timestamp = struct.pack("<d", time.time())
+                timestamp_len = write_var_uint(len(timestamp))
+                await f.write(timestamp_len + timestamp)
 
 
 class TempFileYStore(FileYStore):
@@ -207,17 +212,17 @@ async def init_db(self):
                 await db.execute(f"PRAGMA user_version = {self.version}")
                 await db.commit()
 
-    async def read(self) -> AsyncIterator[Tuple[bytes, bytes]]:  # type: ignore
+    async def read(self) -> AsyncIterator[Tuple[bytes, bytes, float]]:  # type: ignore
         await self.db_initialized
         try:
             async with aiosqlite.connect(self.db_path) as db:
                 async with db.execute(
-                    "SELECT yupdate, metadata FROM yupdates WHERE path = ?", (self.path,)
+                    "SELECT yupdate, metadata, timestamp FROM yupdates WHERE path = ?", (self.path,)
                 ) as cursor:
                     found = False
-                    async for update, metadata in cursor:
+                    async for update, metadata, timestamp in cursor:
                         found = True
-                        yield update, metadata
+                        yield update, metadata, timestamp
                     if not found:
                         raise YDocNotFound
         except BaseException:
diff --git a/ypy_websocket/yutils.py b/ypy_websocket/yutils.py
index 4378cf5..a9cb0f7 100644
--- a/ypy_websocket/yutils.py
+++ b/ypy_websocket/yutils.py
@@ -56,9 +56,7 @@ def __init__(self, stream: bytes):
         self.i0 = 0
 
     def read_var_uint(self) -> int:
-        if self.length == 0:
-            return 0
-        if self.length < 0:
+        if self.length <= 0:
             raise RuntimeError("Y protocol error")
         uint = 0
         i = 0
@@ -73,9 +71,11 @@ def read_var_uint(self) -> int:
         return uint
 
     def read_message(self) -> Optional[bytes]:
+        if self.length == 0:
+            return None
         length = self.read_var_uint()
         if length == 0:
-            return None
+            return b""
         i1 = self.i0 + length
         message = self.stream[self.i0 : i1]  # noqa
         self.i0 = i1