diff --git a/modules/entity/spec/sorted_state_adapter.spec.ts b/modules/entity/spec/sorted_state_adapter.spec.ts
index cc9116b6b0..ce142c9a1b 100644
--- a/modules/entity/spec/sorted_state_adapter.spec.ts
+++ b/modules/entity/spec/sorted_state_adapter.spec.ts
@@ -11,6 +11,20 @@ describe('Sorted State Adapter', () => {
   let adapter: EntityStateAdapter<BookModel>;
   let state: EntityState<BookModel>;
 
+  beforeAll(() => {
+    Object.defineProperty(Array.prototype, 'unwantedField', {
+      enumerable: true,
+      configurable: true,
+      value: 'This should not appear anywhere',
+    });
+  });
+
+  afterAll(() => {
+    Object.defineProperty(Array.prototype, 'unwantedField', {
+      value: undefined,
+    });
+  });
+
   beforeEach(() => {
     adapter = createEntityAdapter({
       selectId: (book: BookModel) => book.id,
diff --git a/modules/entity/src/sorted_state_adapter.ts b/modules/entity/src/sorted_state_adapter.ts
index 15aaecbad0..ed2b297da6 100644
--- a/modules/entity/src/sorted_state_adapter.ts
+++ b/modules/entity/src/sorted_state_adapter.ts
@@ -116,8 +116,7 @@ export function createSortedStateAdapter<T>(selectId: any, sort: any): any {
     const added: T[] = [];
     const updated: Update<T>[] = [];
 
-    for (let index in updates) {
-      const update = updates[index];
+    for (const update of updates) {
       if (update.id in state.entities) {
         updated.push(update);
       } else {