diff --git a/src/compiler/sys.ts b/src/compiler/sys.ts
index e58d08589b..adcedb0286 100644
--- a/src/compiler/sys.ts
+++ b/src/compiler/sys.ts
@@ -25,6 +25,7 @@ declare var require: any;
 declare var module: any;
 declare var process: any;
 declare var global: any;
+declare var __filename: string;
 
 var sys: System = (function () {
 
@@ -224,10 +225,10 @@ var sys: System = (function () {
                 }
             },
             getExecutingFilePath() {
-                return process.mainModule.filename;
+                return __filename;
             },
             getCurrentDirectory() {
-                return (<any>process).cwd();
+                return process.cwd();
             },
             getMemoryUsage() {
                 if (global.gc) {
diff --git a/src/harness/harness.ts b/src/harness/harness.ts
index c535f94bcf..585d0191d8 100644
--- a/src/harness/harness.ts
+++ b/src/harness/harness.ts
@@ -25,7 +25,7 @@
 // this will work in the browser via browserify
 var _chai: typeof chai = require('chai');
 var assert: typeof _chai.assert = _chai.assert;
-declare var __dirname: any; // Node-specific
+declare var __dirname: string; // Node-specific
 var global = <any>Function("return this").call(null);
 
 module Utils {