diff --git a/angular-formly/angular-formly.d.ts b/angular-formly/angular-formly.d.ts
index 8f76b3ccf9..9917d217f4 100644
--- a/angular-formly/angular-formly.d.ts
+++ b/angular-formly/angular-formly.d.ts
@@ -297,6 +297,7 @@ declare module AngularFormly {
 			bound?: any;
 			expression?: any;
 			value?: any;
+			[key: string]: any;
 		};