diff --git a/tests/vector_stores/test_redis_update.py b/tests/vector_stores/test_redis_update.py
new file mode 100644
index 000000000..2983a7fe0
--- /dev/null
+++ b/tests/vector_stores/test_redis_update.py
@@ -0,0 +1,79 @@
+"""Tests for Redis vector store update() — embedding corruption fix.
+
+Regression tests for #4336: when update() is called with vector=None
+(metadata-only update), np.array(None) silently creates a 4-byte scalar,
+overwriting the real embedding. The fix skips the embedding field entirely
+when vector is None.
+"""
+
+from datetime import datetime
+from unittest.mock import MagicMock, patch
+
+import numpy as np
+import pytz
+
+
+@patch("mem0.vector_stores.redis.SearchIndex")
+@patch("mem0.vector_stores.redis.redis.from_url")
+def test_update_with_none_vector_preserves_embedding(mock_redis, mock_search_index):
+    """update() with vector=None should not include embedding in the data."""
+    mock_index = MagicMock()
+    mock_search_index.return_value = mock_index
+
+    from mem0.vector_stores.redis import RedisDB
+
+    db = RedisDB.__new__(RedisDB)
+    db.index = mock_index
+    db.schema = {"index": {"prefix": "mem0:test"}}
+
+    payload = {
+        "hash": "test_hash",
+        "data": "updated_data",
+        "created_at": datetime.now(pytz.timezone("UTC")).isoformat(),
+        "updated_at": datetime.now(pytz.timezone("UTC")).isoformat(),
+        "user_id": "test_user",
+    }
+
+    db.update(vector_id="test_id", vector=None, payload=payload)
+
+    mock_index.load.assert_called_once()
+    call_kwargs = mock_index.load.call_args
+    data_dict = call_kwargs[1]["data"][0] if "data" in call_kwargs[1] else call_kwargs[0][0][0]
+    assert "embedding" not in data_dict, (
+        "embedding should not be in data when vector is None"
+    )
+    assert data_dict["memory_id"] == "test_id"
+
+
+@patch("mem0.vector_stores.redis.SearchIndex")
+@patch("mem0.vector_stores.redis.redis.from_url")
+def test_update_with_vector_includes_embedding(mock_redis, mock_search_index):
+    """update() with a real vector should include embedding in the data."""
+    mock_index = MagicMock()
+    mock_search_index.return_value = mock_index
+
+    from mem0.vector_stores.redis import RedisDB
+
+    db = RedisDB.__new__(RedisDB)
+    db.index = mock_index
+    db.schema = {"index": {"prefix": "mem0:test"}}
+
+    vector = np.random.rand(1536).tolist()
+    payload = {
+        "hash": "test_hash",
+        "data": "updated_data",
+        "created_at": datetime.now(pytz.timezone("UTC")).isoformat(),
+        "updated_at": datetime.now(pytz.timezone("UTC")).isoformat(),
+        "user_id": "test_user",
+    }
+
+    db.update(vector_id="test_id", vector=vector, payload=payload)
+
+    mock_index.load.assert_called_once()
+    call_kwargs = mock_index.load.call_args
+    data_dict = call_kwargs[1]["data"][0] if "data" in call_kwargs[1] else call_kwargs[0][0][0]
+    assert "embedding" in data_dict, (
+        "embedding should be in data when vector is provided"
+    )
+    expected_bytes = np.array(vector, dtype=np.float32).tobytes()
+    assert data_dict["embedding"] == expected_bytes