diff --git a/CHANGELOG.md b/CHANGELOG.md
index 787f1375..4dfb3639 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,7 +8,7 @@ X.Y.Z Release notes
 * Added `Realm.deleteFile` for deleting a Realm (#363).
 
 ### Bug fixes
-* None
+* Adding missing TypeScript declation (#1283).
 
 1.11.1 Release notes (2017-9-1)
 =============================================================
diff --git a/lib/index.d.ts b/lib/index.d.ts
index 614dd52d..f1f2039a 100644
--- a/lib/index.d.ts
+++ b/lib/index.d.ts
@@ -279,12 +279,23 @@ declare namespace Realm.Sync {
         invalidatePermissionOffer(permissionOfferOrToken: PermissionOffer | string): Promise<void>;
     }
 
-    type PermissionCondition = 
-      { [object_type: string]: userId } |
-      { [object_type: string]: metadataKey, [object_type: string]: metadataValue };
-
+    type PermissionCondition = {
+      userId: string  |
+      { metadataKey: string, metadataValue: string }
+    };
+    
     type AccessLevel = 'none' | 'read' | 'write' | 'admin';
 
+    class Permission {
+      readonly id: string;
+      readonly updatedAt: Date;
+      readonly userId: string;
+      readonly path: string;
+      readonly mayRead?: boolean;
+      readonly mayWrite?: boolean;
+      readonly mayManage?: boolean;
+    } 
+
     class PermissionChange {
       id: string;
       createdAt: Date;