diff --git a/types/angular-strap/index.d.ts b/types/angular-strap/index.d.ts
index 2b31f00148..cf0dc25481 100644
--- a/types/angular-strap/index.d.ts
+++ b/types/angular-strap/index.d.ts
@@ -45,6 +45,7 @@ declare namespace mgcrea.ngStrap {
             template?: string;
             templateUrl?: string;
             contentTemplate?: string;
+            prefixClass?:  string;
             prefixEvent?: string;
             id?: string;
             scope?: ng.IScope;