diff --git a/backend/app/models/network_diagram.py b/backend/app/models/network_diagram.py
index 347216da..2a8f3e45 100644
--- a/backend/app/models/network_diagram.py
+++ b/backend/app/models/network_diagram.py
@@ -3,7 +3,7 @@ import uuid
 from datetime import datetime, timezone
 from typing import Any, TYPE_CHECKING
 
-from sqlalchemy import String, Text, Boolean, DateTime, ForeignKey
+from sqlalchemy import String, Text, Boolean, DateTime, ForeignKey, text
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 from sqlalchemy.dialects.postgresql import UUID, JSONB
 
@@ -30,8 +30,8 @@ class NetworkDiagram(Base):
     client_name: Mapped[str | None] = mapped_column(String(255), nullable=True)
     asset_name: Mapped[str | None] = mapped_column(String(255), nullable=True)
     description: Mapped[str | None] = mapped_column(Text, nullable=True)
-    nodes: Mapped[list[dict[str, Any]]] = mapped_column(JSONB, nullable=False, server_default="'[]'")
-    edges: Mapped[list[dict[str, Any]]] = mapped_column(JSONB, nullable=False, server_default="'[]'")
+    nodes: Mapped[list[dict[str, Any]]] = mapped_column(JSONB, nullable=False, server_default=text("'[]'::jsonb"))
+    edges: Mapped[list[dict[str, Any]]] = mapped_column(JSONB, nullable=False, server_default=text("'[]'::jsonb"))
     thumbnail_url: Mapped[str | None] = mapped_column(Text, nullable=True)
     is_archived: Mapped[bool] = mapped_column(
         Boolean, nullable=False, default=False,
diff --git a/backend/tests/conftest.py b/backend/tests/conftest.py
index 9c1f60e6..0adf36ff 100644
--- a/backend/tests/conftest.py
+++ b/backend/tests/conftest.py
@@ -32,14 +32,6 @@ TEST_DATABASE_URL = os.environ.get(
 )
 
 
-@pytest.fixture(scope="session")
-def event_loop() -> Generator:
-    """Create an instance of the default event loop for each test case."""
-    loop = asyncio.get_event_loop_policy().new_event_loop()
-    yield loop
-    loop.close()
-
-
 @pytest.fixture
 async def test_db() -> AsyncGenerator[AsyncSession, None]:
     """