diff --git a/src/cdk/overlay/overlay.ts b/src/cdk/overlay/overlay.ts
index a269bdbdb530..757c174da050 100644
--- a/src/cdk/overlay/overlay.ts
+++ b/src/cdk/overlay/overlay.ts
@@ -51,7 +51,7 @@ export class Overlay {
               private _appRef: ApplicationRef,
               private _injector: Injector,
               private _ngZone: NgZone,
-              @Inject(DOCUMENT) private _document: Document,
+              @Inject(DOCUMENT) private _document: HTMLDocument,
               private _directionality: Directionality) { }
 
   /**