diff --git a/src/database/angularfire2-interfaces.ts b/src/database/angularfire2-interfaces.ts
index 272880e..cc082a3 100644
--- a/src/database/angularfire2-interfaces.ts
+++ b/src/database/angularfire2-interfaces.ts
@@ -2,10 +2,10 @@ import * as firebase from 'firebase/app';
 import { Observable } from 'rxjs/Observable';
 
 export interface FirebaseOperationCases {
-  stringCase: () => firebase.Promise<void>;
-  firebaseCase?: () => firebase.Promise<void>;
-  snapshotCase?: () => firebase.Promise<void>;
-  unwrappedSnapshotCase?: () => firebase.Promise<void>;
+  stringCase: () => Promise<void>;
+  firebaseCase?: () => Promise<void>;
+  snapshotCase?: () => Promise<void>;
+  unwrappedSnapshotCase?: () => Promise<void>;
 }
 
 export interface AFUnwrappedDataSnapshot {
@@ -85,4 +85,4 @@ export type DatabaseSnapshot = firebase.database.DataSnapshot;
 export type DatabaseReference = firebase.database.Reference;
 export type DatabaseQuery = firebase.database.Query;
 export type QueryReference = DatabaseReference | DatabaseQuery;
-export type PathReference = QueryReference | string;
\ No newline at end of file
+export type PathReference = QueryReference | string;