diff --git a/components/renku_data_services/base_api/auth.py b/components/renku_data_services/base_api/auth.py
index f468296f4..16b76b09d 100644
--- a/components/renku_data_services/base_api/auth.py
+++ b/components/renku_data_services/base_api/auth.py
@@ -71,30 +71,6 @@ async def decorated_function(request: Request, *args: _P.args, **kwargs: _P.kwar
     return decorator
 
 
-def validate_path_project_id(
-    f: Callable[Concatenate[Request, _P], Coroutine[Any, Any, _T]],
-) -> Callable[Concatenate[Request, _P], Coroutine[Any, Any, _T]]:
-    """Decorator for a Sanic handler that validates the project_id path parameter."""
-    _path_project_id_regex = re.compile(r"^[A-Za-z0-9]{26}$")
-
-    @wraps(f)
-    async def decorated_function(request: Request, *args: _P.args, **kwargs: _P.kwargs) -> _T:
-        project_id = cast(str | None, kwargs.get("project_id"))
-        if not project_id:
-            raise errors.ProgrammingError(
-                message="Could not find 'project_id' in the keyword arguments for the handler in order to validate it."
-            )
-        if not _path_project_id_regex.match(project_id):
-            raise errors.ValidationError(
-                message=f"The 'project_id' path parameter {project_id} does not match the required "
-                f"regex {_path_project_id_regex}"
-            )
-
-        return await f(request, *args, **kwargs)
-
-    return decorated_function
-
-
 def validate_path_user_id(
     f: Callable[Concatenate[Request, _P], Coroutine[Any, Any, _T]],
 ) -> Callable[Concatenate[Request, _P], Coroutine[Any, Any, _T]]:
diff --git a/components/renku_data_services/project/blueprints.py b/components/renku_data_services/project/blueprints.py
index e07a82ffc..e45e1c4df 100644
--- a/components/renku_data_services/project/blueprints.py
+++ b/components/renku_data_services/project/blueprints.py
@@ -13,7 +13,6 @@
 from renku_data_services.base_api.auth import (
     authenticate,
     only_authenticated,
-    validate_path_project_id,
     validate_path_user_id,
 )
 from renku_data_services.base_api.blueprint import BlueprintFactoryResponse, CustomBlueprint
@@ -80,12 +79,11 @@ def get_one(self) -> BlueprintFactoryResponse:
         """Get a specific project."""
 
         @authenticate(self.authenticator)
-        @validate_path_project_id
         @extract_if_none_match
         async def _get_one(
-            _: Request, user: base_models.APIUser, project_id: str, etag: str | None
+            _: Request, user: base_models.APIUser, project_id: ULID, etag: str | None
         ) -> JSONResponse | HTTPResponse:
-            project = await self.project_repo.get_project(user=user, project_id=ULID.from_str(project_id))
+            project = await self.project_repo.get_project(user=user, project_id=project_id)
 
             if project.etag is not None and project.etag == etag:
                 return HTTPResponse(status=304)
@@ -210,14 +208,11 @@ def get_permissions(self) -> BlueprintFactoryResponse:
         """Get the permissions of the current user on the project."""
 
         @authenticate(self.authenticator)
-        @validate_path_project_id
-        async def _get_permissions(_: Request, user: base_models.APIUser, project_id: str) -> JSONResponse:
-            permissions = await self.project_repo.get_project_permissions(
-                user=user, project_id=ULID.from_str(project_id)
-            )
+        async def _get_permissions(_: Request, user: base_models.APIUser, project_id: ULID) -> JSONResponse:
+            permissions = await self.project_repo.get_project_permissions(user=user, project_id=project_id)
             return validated_json(apispec.ProjectPermissions, permissions)
 
-        return "/projects/<project_id>/permissions", ["GET"], _get_permissions
+        return "/projects/<project_id:ulid>/permissions", ["GET"], _get_permissions
 
     @staticmethod
     def _dump_project(project: project_models.Project) -> dict[str, Any]: