diff --git a/spec/helpers/test-helper.ts b/spec/helpers/test-helper.ts
index ea290e8f1d7..37f1145cb6f 100644
--- a/spec/helpers/test-helper.ts
+++ b/spec/helpers/test-helper.ts
@@ -71,6 +71,11 @@ export function fit(expectation: string, assertion?: (done?: DoneSignature) => v
   }
 }
 
+export function type(assertion: Function): void {
+  //intentionally does not execute to avoid unexpected side effect occurs by subscription,
+  //or infinite source. Suffecient to check build time only.
+}
+
 export function lowerCaseO<T>(...args): Rx.Observable<T> {
   const values = [].slice.apply(arguments);
 
diff --git a/spec/operators/toArray-spec.ts b/spec/operators/toArray-spec.ts
index 65038547eba..20c6f6791c0 100644
--- a/spec/operators/toArray-spec.ts
+++ b/spec/operators/toArray-spec.ts
@@ -1,6 +1,6 @@
 import * as Rx from '../../dist/cjs/Rx';
 import {hot, cold, expectObservable, expectSubscriptions} from '../helpers/marble-testing';
-import {it, asDiagram} from '../helpers/test-helper';
+import {it, asDiagram, type} from '../helpers/test-helper';
 
 const Observable = Rx.Observable;
 
@@ -101,4 +101,12 @@ describe('toArray', () => {
     expectObservable(e1.toArray()).toBe(expected);
     expectSubscriptions(e1.subscriptions).toBe(e1subs);
   });
+
+  type(() => {
+    const typeValue = {
+      val: 3
+    };
+
+    Observable.of(typeValue).toArray().subscribe(x => { x[0].val.toString(); });
+  });
 });