diff --git a/example/extensions/index.ts b/example/extensions/index.ts
index 31d3423..c8ec283 100644
--- a/example/extensions/index.ts
+++ b/example/extensions/index.ts
@@ -27,5 +27,6 @@ THE SOFTWARE.
 ---------------------------------------------------------------------------*/
 
 export * from './intersect-allof'
+export * from './readonly-object'
 export * from './union-oneof'
 export * from './union-enum'
diff --git a/example/extensions/readonly-object.ts b/example/extensions/readonly-object.ts
new file mode 100644
index 0000000..cf92fd2
--- /dev/null
+++ b/example/extensions/readonly-object.ts
@@ -0,0 +1,56 @@
+/*--------------------------------------------------------------------------
+
+@sinclair/typebox/extensions
+
+The MIT License (MIT)
+
+Copyright (c) 2017-2023 Haydn Paterson (sinclair) <haydn.developer@gmail.com>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+---------------------------------------------------------------------------*/
+
+import { Type, TSchema, TObject, TProperties, Modifier, TReadonly, TReadonlyOptional, TOptional } from '@sinclair/typebox'
+
+// prettier-ignore
+export type TReadonlyObject<T extends TObject> = TObject<{
+  [K in keyof T['properties']]: 
+    T['properties'][K] extends TReadonlyOptional<infer U> ? TReadonlyOptional<U> : 
+    T['properties'][K] extends TReadonly<infer U>         ? TReadonly<U> : 
+    T['properties'][K] extends TOptional<infer U>         ? TReadonlyOptional<U> : 
+    TReadonly<T['properties'][K]>
+}>
+
+/** Remaps all properties of an object to be readonly */
+export function ReadonlyObject<T extends TObject>(schema: T): TReadonlyObject<T> {
+  return Type.Object(
+    Object.keys(schema.properties).reduce((acc, key) => {
+      const property = schema.properties[key] as TSchema
+      const modifier = property[Modifier]
+      // prettier-ignore
+      const mapped = (
+        (modifier === 'ReadonlyOptional') ? { ...property, [Modifier]: 'ReadonlyOptional' } :
+        (modifier === 'Readonly')         ? { ...property, [Modifier]: 'Readonly' } :
+        (modifier === 'Optional')         ? { ...property, [Modifier]: 'ReadonlyOptional' } :
+        ({...property, [Modifier]: 'Readonly' })
+      )
+      return { ...acc, [key]: mapped }
+    }, {} as TProperties),
+  ) as TReadonlyObject<T>
+}