diff --git a/angular-formly/angular-formly.d.ts b/angular-formly/angular-formly.d.ts
index f42b35a89e..423e6ff9b3 100644
--- a/angular-formly/angular-formly.d.ts
+++ b/angular-formly/angular-formly.d.ts
@@ -101,13 +101,13 @@ declare module AngularFormly {
 		type?: string;
 
 		//expression types
-		onBlur?: string;
-		onChange?: string;
-		onClick?: string;
-		onFocus?: string;
-		onKeydown?: string;
-		onKeypress?: string;
-		onKeyup?: string;
+		onBlur?: string | IExpressionFunction;
+		onChange?: string | IExpressionFunction;
+		onClick?: string | IExpressionFunction;
+		onFocus?: string | IExpressionFunction;
+		onKeydown?: string | IExpressionFunction;
+		onKeypress?: string | IExpressionFunction;
+		onKeyup?: string | IExpressionFunction;
 
 		//Bootstrap types
 		label?: string;