diff --git a/tests/test_qdrant_client.py b/tests/test_qdrant_client.py
index 95877b7e..098c8af2 100644
--- a/tests/test_qdrant_client.py
+++ b/tests/test_qdrant_client.py
@@ -2051,6 +2051,35 @@ def auth_token_provider():
     client.unlock_storage()
     assert token == "token_2"
 
+
+def test_async_auth_token_provider():
+    """Check that initialization fails if async auth_token_provider is provided to sync client."""
+    token = ""
+
+    async def auth_token_provider():
+        nonlocal token
+        await asyncio.sleep(0.1)
+        token = "test_token"
+        return token
+
+    client = QdrantClient(auth_token_provider=auth_token_provider)
+
+    with pytest.raises(
+        qdrant_client.http.exceptions.ResponseHandlingException,
+        match="Synchronous token provider is not set.",
+    ):
+        client.get_collections()
+
+    assert token == ""
+
+    client = QdrantClient(auth_token_provider=auth_token_provider, prefer_grpc=True)
+    with pytest.raises(
+        ValueError, match="Synchronous channel requires synchronous auth token provider."
+    ):
+        client.get_collections()
+
+    assert token == ""
+
 @pytest.mark.parametrize("prefer_grpc", [True, False])
 def test_read_consistency(prefer_grpc):
     fixture_points = generate_fixtures(vectors_sizes=DIM, num=NUM_VECTORS)