diff --git a/src/cdk/overlay/overlay.ts b/src/cdk/overlay/overlay.ts
index 2e9f7e52696b..9b7333d2227e 100644
--- a/src/cdk/overlay/overlay.ts
+++ b/src/cdk/overlay/overlay.ts
@@ -41,7 +41,7 @@ let nextUniqueId = 0;
  *
  * An overlay *is* a PortalOutlet, so any kind of Portal can be loaded into one.
  */
-@Injectable()
+@Injectable({providedIn: 'root'})
 export class Overlay {
   private _appRef: ApplicationRef;