diff --git a/src/internal/operators/dematerialize.ts b/src/internal/operators/dematerialize.ts
index 116b60bfd6..28c2c867f2 100644
--- a/src/internal/operators/dematerialize.ts
+++ b/src/internal/operators/dematerialize.ts
@@ -25,11 +25,11 @@ import { OperatorSubscriber } from './OperatorSubscriber';
  * Convert an Observable of Notifications to an actual Observable
  *
  * ```ts
- * import { of, dematerialize } from 'rxjs';
+ * import { NextNotification, ErrorNotification, of, dematerialize } from 'rxjs';
  *
- * const notifA = { kind: 'N', value: 'A' };
- * const notifB = { kind: 'N', value: 'B' };
- * const notifE = { kind: 'E', error: new TypeError('x.toUpperCase is not a function') }
+ * const notifA = <NextNotification<string>>{ kind: 'N', value: 'A' };
+ * const notifB = <NextNotification<string>>{ kind: 'N', value: 'B' };
+ * const notifE = <ErrorNotification>{ kind: 'E', error: new TypeError('x.toUpperCase is not a function') };
  *
  * const materialized = of(notifA, notifB, notifE);
  *