diff --git a/backend/models.py b/backend/models.py
index bbe5b91..87bfe8e 100644
--- a/backend/models.py
+++ b/backend/models.py
@@ -1,4 +1,4 @@
-from datetime import datetime, date, time, UTC
+from datetime import datetime, date, time, timezone
 from enum import Enum as PyEnum
 from typing import TypedDict
 from sqlalchemy import Integer, String, Float, DateTime, Date, Time, ForeignKey, Table, Column, Enum, UniqueConstraint, select
@@ -197,7 +197,7 @@ class SumRecord(Base):
     b: Mapped[float] = mapped_column(Float, nullable=False)
     result: Mapped[float] = mapped_column(Float, nullable=False)
     created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), default=lambda: datetime.now(UTC)
+        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
     )
 
 
@@ -209,7 +209,7 @@ class CounterRecord(Base):
     value_before: Mapped[int] = mapped_column(Integer, nullable=False)
     value_after: Mapped[int] = mapped_column(Integer, nullable=False)
     created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), default=lambda: datetime.now(UTC)
+        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
     )
 
 
@@ -244,7 +244,7 @@ class Invite(Base):
     
     # Timestamps
     created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), default=lambda: datetime.now(UTC)
+        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
     )
     spent_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
     revoked_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
@@ -262,12 +262,12 @@ class Availability(Base):
     start_time: Mapped[time] = mapped_column(Time, nullable=False)
     end_time: Mapped[time] = mapped_column(Time, nullable=False)
     created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), default=lambda: datetime.now(UTC)
+        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
     )
     updated_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), 
-        default=lambda: datetime.now(UTC),
-        onupdate=lambda: datetime.now(UTC)
+        default=lambda: datetime.now(timezone.utc),
+        onupdate=lambda: datetime.now(timezone.utc)
     )
 
 
@@ -290,6 +290,6 @@ class Appointment(Base):
         Enum(AppointmentStatus), nullable=False, default=AppointmentStatus.BOOKED
     )
     created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), default=lambda: datetime.now(UTC)
+        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
     )
     cancelled_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
diff --git a/backend/routes/auth.py b/backend/routes/auth.py
index 5763cb2..be8c138 100644
--- a/backend/routes/auth.py
+++ b/backend/routes/auth.py
@@ -1,5 +1,5 @@
 """Authentication routes for register, login, logout, and current user."""
-from datetime import datetime, UTC
+from datetime import datetime, timezone
 
 from fastapi import APIRouter, Depends, HTTPException, Response, status
 from sqlalchemy import select
@@ -90,7 +90,7 @@ async def register(
     # Mark invite as spent
     invite.status = InviteStatus.SPENT
     invite.used_by_id = user.id
-    invite.spent_at = datetime.now(UTC)
+    invite.spent_at = datetime.now(timezone.utc)
 
     await db.commit()
     await db.refresh(user)
diff --git a/backend/routes/invites.py b/backend/routes/invites.py
index 46f9948..4fde96e 100644
--- a/backend/routes/invites.py
+++ b/backend/routes/invites.py
@@ -1,5 +1,5 @@
 """Invite routes for public check, user invites, and admin management."""
-from datetime import datetime, UTC
+from datetime import datetime, timezone
 
 from fastapi import APIRouter, Depends, HTTPException, status, Query
 from sqlalchemy import select, func, desc
@@ -228,7 +228,7 @@ async def revoke_invite(
         )
 
     invite.status = InviteStatus.REVOKED
-    invite.revoked_at = datetime.now(UTC)
+    invite.revoked_at = datetime.now(timezone.utc)
     await db.commit()
     await db.refresh(invite)