diff --git a/mocha/mocha-tests.ts b/mocha/mocha-tests.ts
index 750a417fe..dffd86e44 100644
--- a/mocha/mocha-tests.ts
+++ b/mocha/mocha-tests.ts
@@ -218,7 +218,7 @@ function test_require_fluentParams() {
 function test_run_withOnComplete() {
     var instance = new MochaDef();
 
-    instance.run((failures: any[]): void => {
+    instance.run((failures: number): void => {
         console.log(failures);
     });
 }
\ No newline at end of file
diff --git a/mocha/mocha.d.ts b/mocha/mocha.d.ts
index 2e6fa9c58..bc13ea774 100644
--- a/mocha/mocha.d.ts
+++ b/mocha/mocha.d.ts
@@ -140,7 +140,7 @@ declare module "mocha" {
         asyncOnly(value: boolean): MochaInstance;
         noHighlighting(value: boolean): MochaInstance;
 
-        run(onComplete?: (failures: any[]) => void): void;
+        run(onComplete?: (failures: number) => void): void;
     }
 
     export = MochaInstance;