diff --git a/src/api/categories.py b/src/api/categories.py
index 549c38d..d9717ec 100644
--- a/src/api/categories.py
+++ b/src/api/categories.py
@@ -3,7 +3,7 @@ from typing import Annotated, cast, final
 
 from beanie import Link, PydanticObjectId
 from fastapi import APIRouter, Body, HTTPException, Response, status
-from pydantic import BaseModel, StringConstraints, field_validator
+from pydantic import BaseModel, StringConstraints, field_serializer, field_validator
 from pydantic_extra_types.color import Color
 
 from src.api.auth.dependencies import LoggedInDep
@@ -37,6 +37,11 @@ class _BaseCategoryData(BaseModel):
             raise ValueError("Alpha channel is not allowed in colors")
         return value
 
+    @field_serializer("color")
+    def serialize_color(self, value: Color) -> str:
+        """Serialize the color to a long hex string (#abcdef)."""
+        return value.as_hex(format="long")
+
 
 @final
 class CategoryData(_BaseCategoryData):
@@ -116,7 +121,7 @@ async def get_user_categories(user_id: PydanticObjectId, user: CurrentUserDep) -
             detail="You can only access your own categories",
         )
 
-    categories = await Category.find(expr(Category.user).id == user.id).to_list()
+    categories = await Category.find(expr(Category.user).id == user.id, fetch_links=True).to_list()
     return [CategoryData.from_category(category) for category in categories]
 
 
diff --git a/src/api/events.py b/src/api/events.py
index 0815b68..e00eed3 100644
--- a/src/api/events.py
+++ b/src/api/events.py
@@ -4,7 +4,7 @@ from typing import Annotated, cast, final
 from beanie import DeleteRules, Link, PydanticObjectId
 from fastapi import APIRouter, Body, HTTPException, Query, status
 from fastapi.responses import Response
-from pydantic import BaseModel, StringConstraints, field_validator
+from pydantic import BaseModel, StringConstraints, field_serializer, field_validator
 from pydantic_extra_types.color import Color
 
 from src.api.auth.dependencies import LoggedInDep
@@ -45,6 +45,11 @@ class _BaseEventData(BaseModel):
             raise ValueError("Alpha channel is not allowed in colors")
         return value
 
+    @field_serializer("color")
+    def serialize_color(self, value: Color) -> str:
+        """Serialize the color to a long hex string (#abcdef)."""
+        return value.as_hex(format="long")
+
 
 @final
 class EventData(_BaseEventData):