diff --git a/src/utils/types.test.ts b/src/utils/types.test.ts
index 709ea6896..80fca294d 100644
--- a/src/utils/types.test.ts
+++ b/src/utils/types.test.ts
@@ -101,6 +101,11 @@ describe('JSONParsed', () => {
       type Expected = (number | null)[]
       expectTypeOf<Actual>().toEqualTypeOf<Expected>()
     })
+    it('should convert { key: readonly T[]} correctly', () => {
+      type Actual = JSONParsed<{ key: readonly number[] }>
+      type Expected = { key: readonly number[] }
+      expectTypeOf<Actual>().toEqualTypeOf<Expected>()
+    })
   })
 
   describe('tuple', () => {
diff --git a/src/utils/types.ts b/src/utils/types.ts
index 8beb970a6..3fd17a949 100644
--- a/src/utils/types.ts
+++ b/src/utils/types.ts
@@ -56,6 +56,8 @@ export type JSONParsed<T> = T extends { toJSON(): infer J }
   ? [JSONParsed<InvalidToNull<R>>, ...JSONParsed<U>]
   : T extends Array<infer U>
   ? Array<JSONParsed<InvalidToNull<U>>>
+  : T extends ReadonlyArray<infer U>
+  ? ReadonlyArray<JSONParsed<InvalidToNull<U>>>
   : T extends Set<unknown> | Map<unknown, unknown>
   ? {}
   : T extends object