diff --git a/src/shared/mixins.py b/src/shared/mixins.py
index 8deae15..78d2e30 100644
--- a/src/shared/mixins.py
+++ b/src/shared/mixins.py
@@ -5,4 +5,7 @@
 
 class TimestampMixin:
     created_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc))
-    updated_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc))
+    updated_at: datetime = Field(
+        default_factory=lambda: datetime.now(timezone.utc),
+        sa_column_kwargs={"onupdate": lambda: datetime.now(timezone.utc)},
+    )
diff --git a/tests/shared/__init__.py b/tests/shared/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/shared/test_mixins.py b/tests/shared/test_mixins.py
new file mode 100644
index 0000000..658c41d
--- /dev/null
+++ b/tests/shared/test_mixins.py
@@ -0,0 +1,67 @@
+from asyncio import sleep
+
+import pytest
+from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine
+from sqlalchemy.orm import sessionmaker
+from sqlmodel import Field, SQLModel
+
+from src.shared.mixins import TimestampMixin
+
+
+class SampleModel(SQLModel, TimestampMixin, table=True):
+    id: int | None = Field(default=None, primary_key=True)
+    name: str
+
+
+@pytest.fixture
+async def mixin_db():
+    engine = create_async_engine(
+        "sqlite+aiosqlite:///:memory:",
+        echo=False,
+        connect_args={"check_same_thread": False},
+    )
+    async_session = sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)
+
+    async with engine.begin() as conn:
+        await conn.run_sync(SQLModel.metadata.create_all)
+
+    yield async_session
+
+    async with engine.begin() as conn:
+        await conn.run_sync(SQLModel.metadata.drop_all)
+
+
+async def test_timestamp_mixin_updated_at_updates(mixin_db):
+    async with mixin_db() as session:
+        record = SampleModel(name="original")
+        session.add(record)
+        await session.commit()
+        await session.refresh(record)
+        initial_updated_at = record.updated_at
+
+        await sleep(0.01)
+
+        record.name = "modified"
+        session.add(record)
+        await session.commit()
+        await session.refresh(record)
+
+        assert record.updated_at > initial_updated_at
+
+
+async def test_timestamp_mixin_created_at_unchanged(mixin_db):
+    async with mixin_db() as session:
+        record = SampleModel(name="original")
+        session.add(record)
+        await session.commit()
+        await session.refresh(record)
+        initial_created_at = record.created_at
+
+        await sleep(0.01)
+
+        record.name = "modified"
+        session.add(record)
+        await session.commit()
+        await session.refresh(record)
+
+        assert record.created_at == initial_created_at