diff --git a/x-pack/packages/ml/nested_property/src/set_nested_property.test.ts b/x-pack/packages/ml/nested_property/src/set_nested_property.test.ts
index 180454d55c457..eb28202d7672d 100644
--- a/x-pack/packages/ml/nested_property/src/set_nested_property.test.ts
+++ b/x-pack/packages/ml/nested_property/src/set_nested_property.test.ts
@@ -75,6 +75,6 @@ describe('object_utils', () => {
 
     const test13 = setNestedProperty(getTestObj(), 'the.prototype', 'update');
     expect(test13.the).toBe('update');
-    expect(test13.the.prototype.update).toBe(undefined);
+    expect(test13.the.prototype?.update).toBe(undefined);
   });
 });