diff --git a/backend/app/db.py b/backend/app/db.py
index fa51df5..e44dd35 100644
--- a/backend/app/db.py
+++ b/backend/app/db.py
@@ -1,9 +1,23 @@
+import sys
+
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
 from sqlalchemy.orm import DeclarativeBase
+from sqlalchemy.pool import NullPool
 
 from app.config import settings
 
-engine = create_async_engine(settings.database_url, echo=False)
+# pytest-asyncio gives each test function its own event loop by default, but
+# this engine (and its connection pool) is a module-level singleton created
+# once and reused across every test. asyncpg connections are bound to the
+# event loop they were opened on, so pooling them across per-test loops
+# raises "got Future attached to a different loop". NullPool sidesteps this
+# by opening a fresh connection per checkout instead of reusing one from a
+# prior loop. Only applied under pytest; production keeps normal pooling.
+_engine_kwargs = {"echo": False}
+if "pytest" in sys.modules:
+    _engine_kwargs["poolclass"] = NullPool
+
+engine = create_async_engine(settings.database_url, **_engine_kwargs)
 async_session_maker = async_sessionmaker(engine, expire_on_commit=False)