diff --git a/mocha/mocha.d.ts b/mocha/mocha.d.ts
index 572edbc71f..50fb3fcc47 100644
--- a/mocha/mocha.d.ts
+++ b/mocha/mocha.d.ts
@@ -12,27 +12,27 @@ declare var describe : {
 
 declare var it: {
     (expectation: string, assertion?: () => void): void;
-    (expectation: string, assertion?: (done: () => void) => void): void;
+    (expectation: string, assertion?: (done: (failReason?) => void) => void): void;
     only(expectation: string, assertion?: () => void): void;
-    only(expectation: string, assertion?: (done: () => void) => void): void;
+	only(expectation: string, assertion?: (done: (failReason?) => void) => void): void;
     skip(expectation: string, assertion?: () => void): void;
-    skip(expectation: string, assertion?: (done: () => void) => void): void;
+	skip(expectation: string, assertion?: (done: (failReason?) => void) => void): void;
     timeout(ms: number);
 };
 
 declare function before(action: () => void): void;
 
-declare function before(action: (done: () => void) => void): void;
+declare function before(action: (done: (failReason?) => void) => void): void;
 
 declare function after(action: () => void): void;
 
-declare function after(action: (done: () => void) => void): void;
+declare function after(action: (done: (failReason?) => void) => void): void;
 
 declare function beforeEach(action: () => void): void;
 
-declare function beforeEach(action: (done: () => void) => void): void;
+declare function beforeEach(action: (done: (failReason?) => void) => void): void;
 
 declare function afterEach(action: () => void): void;
 
-declare function afterEach(action: (done: () => void) => void): void;
+declare function afterEach(action: (done: (failReason?) => void) => void): void;