diff --git a/pyodk/_endpoints/bases.py b/pyodk/_endpoints/bases.py
index 126debc..cbefc84 100644
--- a/pyodk/_endpoints/bases.py
+++ b/pyodk/_endpoints/bases.py
@@ -1,4 +1,4 @@
-from pydantic import BaseModel
+from pydantic import BaseModel, ConfigDict
 
 from pyodk._utils.session import Session
 
@@ -6,9 +6,16 @@
 class Model(BaseModel):
     """Base configuration for data model classes."""
 
-    class Config:
-        arbitrary_types_allowed = True
-        validate_assignment = True
+    model_config = ConfigDict(arbitrary_types_allowed=True, validate_assignment=True)
+
+
+class FrozenModel(Model):
+    """Make the base configuration model faux-immutable.
+
+    NOTE in pydantic v2 inherited model_config are *merged*.
+    """
+
+    model_config = ConfigDict(frozen=True)
 
 
 class Manager:
diff --git a/pyodk/_endpoints/comments.py b/pyodk/_endpoints/comments.py
index adada4a..4224a57 100644
--- a/pyodk/_endpoints/comments.py
+++ b/pyodk/_endpoints/comments.py
@@ -15,10 +15,7 @@ class Comment(bases.Model):
     createdAt: datetime
 
 
-class URLs(bases.Model):
-    class Config:
-        frozen = True
-
+class URLs(bases.FrozenModel):
     list: str = "projects/{project_id}/forms/{form_id}/submissions/{instance_id}/comments"
     post: str = "projects/{project_id}/forms/{form_id}/submissions/{instance_id}/comments"
 
diff --git a/pyodk/_endpoints/entities.py b/pyodk/_endpoints/entities.py
index 35b7640..cbe67cf 100644
--- a/pyodk/_endpoints/entities.py
+++ b/pyodk/_endpoints/entities.py
@@ -65,10 +65,7 @@ class Entity(bases.Model):
     deletedAt: datetime | None = None
 
 
-class URLs(bases.Model):
-    class Config:
-        frozen = True
-
+class URLs(bases.FrozenModel):
     _entity_name: str = "projects/{project_id}/datasets/{el_name}"
     _entities: str = f"{_entity_name}/entities"
     list: str = _entities
diff --git a/pyodk/_endpoints/entity_list_properties.py b/pyodk/_endpoints/entity_list_properties.py
index 09032fc..bfe65aa 100644
--- a/pyodk/_endpoints/entity_list_properties.py
+++ b/pyodk/_endpoints/entity_list_properties.py
@@ -16,10 +16,7 @@ class EntityListProperty(bases.Model):
     forms: list[str]
 
 
-class URLs(bases.Model):
-    class Config:
-        frozen = True
-
+class URLs(bases.FrozenModel):
     post: str = "projects/{project_id}/datasets/{entity_list_name}/properties"
 
 
diff --git a/pyodk/_endpoints/entity_lists.py b/pyodk/_endpoints/entity_lists.py
index ee478c9..9c58f7d 100644
--- a/pyodk/_endpoints/entity_lists.py
+++ b/pyodk/_endpoints/entity_lists.py
@@ -22,10 +22,7 @@ class EntityList(bases.Model):
     properties: list[EntityListProperty] | None = None
 
 
-class URLs(bases.Model):
-    class Config:
-        frozen = True
-
+class URLs(bases.FrozenModel):
     _entity_list = "projects/{project_id}/datasets"
     list: str = _entity_list
     post: str = _entity_list
diff --git a/pyodk/_endpoints/form_assignments.py b/pyodk/_endpoints/form_assignments.py
index 7bb802f..0ef0c59 100644
--- a/pyodk/_endpoints/form_assignments.py
+++ b/pyodk/_endpoints/form_assignments.py
@@ -8,10 +8,7 @@
 log = logging.getLogger(__name__)
 
 
-class URLs(bases.Model):
-    class Config:
-        frozen = True
-
+class URLs(bases.FrozenModel):
     _form: str = "projects/{project_id}/forms/{form_id}"
     post: str = f"{_form}/assignments/{{role_id}}/{{user_id}}"
 
diff --git a/pyodk/_endpoints/form_draft_attachments.py b/pyodk/_endpoints/form_draft_attachments.py
index cc6ae9a..f6e650d 100644
--- a/pyodk/_endpoints/form_draft_attachments.py
+++ b/pyodk/_endpoints/form_draft_attachments.py
@@ -9,10 +9,7 @@
 log = logging.getLogger(__name__)
 
 
-class URLs(bases.Model):
-    class Config:
-        frozen = True
-
+class URLs(bases.FrozenModel):
     _form: str = "projects/{project_id}/forms/{form_id}"
     post: str = f"{_form}/draft/attachments/{{fname}}"
 
diff --git a/pyodk/_endpoints/form_drafts.py b/pyodk/_endpoints/form_drafts.py
index 2d918dd..b1ddf46 100644
--- a/pyodk/_endpoints/form_drafts.py
+++ b/pyodk/_endpoints/form_drafts.py
@@ -81,10 +81,7 @@ def get_definition_data(
     return definition_data, content_type, file_path_stem
 
 
-class URLs(bases.Model):
-    class Config:
-        frozen = True
-
+class URLs(bases.FrozenModel):
     _form: str = "projects/{project_id}/forms/{form_id}"
     post: str = f"{_form}/draft"
     post_publish: str = f"{_form}/draft/publish"
diff --git a/pyodk/_endpoints/forms.py b/pyodk/_endpoints/forms.py
index 98eedb0..e351725 100644
--- a/pyodk/_endpoints/forms.py
+++ b/pyodk/_endpoints/forms.py
@@ -31,10 +31,7 @@ class Form(bases.Model):
     publishedAt: datetime | None
 
 
-class URLs(bases.Model):
-    class Config:
-        frozen = True
-
+class URLs(bases.FrozenModel):
     forms: str = "projects/{project_id}/forms"
     get: str = f"{forms}/{{form_id}}"
 
diff --git a/pyodk/_endpoints/project_app_users.py b/pyodk/_endpoints/project_app_users.py
index 025bbed..1e20ae4 100644
--- a/pyodk/_endpoints/project_app_users.py
+++ b/pyodk/_endpoints/project_app_users.py
@@ -20,10 +20,7 @@ class ProjectAppUser(bases.Model):
     deletedAt: datetime | None
 
 
-class URLs(bases.Model):
-    class Config:
-        frozen = True
-
+class URLs(bases.FrozenModel):
     list: str = "projects/{project_id}/app-users"
     post: str = "projects/{project_id}/app-users"
 
diff --git a/pyodk/_endpoints/projects.py b/pyodk/_endpoints/projects.py
index f390d2d..50f3a74 100644
--- a/pyodk/_endpoints/projects.py
+++ b/pyodk/_endpoints/projects.py
@@ -27,10 +27,7 @@ class Project(bases.Model):
     deletedAt: datetime | None = None
 
 
-class URLs(bases.Model):
-    class Config:
-        frozen = True
-
+class URLs(bases.FrozenModel):
     list: str = "projects"
     get: str = "projects/{project_id}"
     get_data: str = "projects/{project_id}/forms/{form_id}.svc/{table_name}"
diff --git a/pyodk/_endpoints/submissions.py b/pyodk/_endpoints/submissions.py
index c59e74b..3ec4609 100644
--- a/pyodk/_endpoints/submissions.py
+++ b/pyodk/_endpoints/submissions.py
@@ -24,10 +24,7 @@ class Submission(bases.Model):
     updatedAt: datetime | None = None
 
 
-class URLs(bases.Model):
-    class Config:
-        frozen = True
-
+class URLs(bases.FrozenModel):
     _form: str = "projects/{project_id}/forms/{form_id}"
     list: str = f"{_form}/submissions"
     get: str = f"{_form}/submissions/{{instance_id}}"