diff --git a/chai-as-promised/chai-as-promised.d.ts b/chai-as-promised/chai-as-promised.d.ts
index 6ff150eb44..106bbf41e8 100644
--- a/chai-as-promised/chai-as-promised.d.ts
+++ b/chai-as-promised/chai-as-promised.d.ts
@@ -14,6 +14,7 @@ declare module Chai {
 
     interface Assertion {
         become(expected: any): Assertion;
+        fulfilled: Assertion;
         rejected: Assertion;
         rejectedWith(expected: any): Assertion;
         notify(fn: Function): Assertion;