diff --git a/src/polymarket/_internal/streams/clob/user_protocol.py b/src/polymarket/_internal/streams/clob/user_protocol.py
index cb7d9c2..87f1a41 100644
--- a/src/polymarket/_internal/streams/clob/user_protocol.py
+++ b/src/polymarket/_internal/streams/clob/user_protocol.py
@@ -35,15 +35,17 @@ def derive_state(subs: Iterable[UserSubscription]) -> UserServerState:
 
 
 def build_initial_frame(state: UserServerState, credentials: ApiKeyCreds) -> dict[str, Any]:
-    return {
+    frame: dict[str, Any] = {
         "type": "user",
         "auth": {
             "apiKey": credentials.key,
             "secret": credentials.secret,
             "passphrase": credentials.passphrase,
         },
-        "markets": list(state.markets),
     }
+    if not state.include_all_markets:
+        frame["markets"] = list(state.markets)
+    return frame
 
 
 def _build_subscribe_update(markets: Iterable[str]) -> dict[str, Any]:
diff --git a/tests/unit/test_streams_user_manager.py b/tests/unit/test_streams_user_manager.py
index 7411fe6..c687ed0 100644
--- a/tests/unit/test_streams_user_manager.py
+++ b/tests/unit/test_streams_user_manager.py
@@ -75,7 +75,7 @@ async def run() -> None:
     }
 
 
-def test_initial_frame_for_all_markets_uses_empty_markets() -> None:
+def test_initial_frame_for_all_markets_omits_market_filter() -> None:
     received: list[dict[str, Any]] = []
 
     async def handler(ws: ServerConnection) -> None:
@@ -95,7 +95,7 @@ async def run() -> None:
                 await mgr.close()
 
     asyncio.run(run())
-    assert received[0]["markets"] == []
+    assert "markets" not in received[0]
 
 
 def test_credentials_resolved_fresh_per_connection() -> None:
@@ -204,7 +204,7 @@ async def run() -> None:
 
     asyncio.run(run())
     assert received[0]["type"] == "user"
-    assert received[0]["markets"] == []
+    assert "markets" not in received[0]
     assert {"operation": "subscribe", "markets": ["m1"]} in received
 
 
diff --git a/tests/unit/test_streams_user_protocol.py b/tests/unit/test_streams_user_protocol.py
index cbf5f1e..35dbd1a 100644
--- a/tests/unit/test_streams_user_protocol.py
+++ b/tests/unit/test_streams_user_protocol.py
@@ -63,9 +63,12 @@ def test_initial_frame_shape() -> None:
     }
 
 
-def test_initial_frame_all_markets_sends_empty_markets() -> None:
+def test_initial_frame_all_markets_omits_market_filter() -> None:
     state = UserServerState(include_all_markets=True, markets=())
-    assert build_initial_frame(state, _CREDS)["markets"] == []
+    assert build_initial_frame(state, _CREDS) == {
+        "type": "user",
+        "auth": {"apiKey": "K", "secret": "S", "passphrase": "P"},
+    }
 
 
 def test_diff_no_change() -> None: