diff --git a/package.json b/package.json
index 442ee15..1fcd315 100644
--- a/package.json
+++ b/package.json
@@ -32,9 +32,11 @@
   "license": "MIT",
   "dependencies": {
     "ast-source": "^2.0.0",
-    "comment-to-assert": "^1.0.2",
+    "comment-to-assert": "^1.1.0",
     "concat-stream": "^1.5.0",
+    "escodegen": "^1.8.0",
     "espower": "^1.0.6",
+    "espree": "^3.1.5",
     "esprima": "^2.5.0",
     "estraverse": "^4.1.0",
     "power-assert-formatter": "^1.0.1"
diff --git a/src/inject-assert.js b/src/inject-assert.js
index 84de9f0..07e6a1d 100644
--- a/src/inject-assert.js
+++ b/src/inject-assert.js
@@ -1,7 +1,5 @@
 // LICENSE : MIT
 "use strict";
-import traverse from "estraverse"
-import {Syntax} from "estraverse"
 import {parse} from "esprima"
 export function injectAssertModule(AST) {
     var powerAssertDeclaration = parse(`var assert = require("power-assert")`);
diff --git a/src/power-doctest.js b/src/power-doctest.js
index ed5e04e..552c98f 100644
--- a/src/power-doctest.js
+++ b/src/power-doctest.js
@@ -4,7 +4,7 @@ import {toAssertFromAST} from "comment-to-assert"
 import {injectAssertModule} from "./inject-assert"
 import espower from "espower"
 import assert from "assert"
-import ASTSource from "ast-source"
+import ASTSource from "ast-source";
 import {ASTDataContainer} from "ast-source"
 export function convertCode(code, filePath) {
     var source = new ASTSource(code, {
diff --git a/test/power-doctest.test.js b/test/power-doctest.test.js
index c513942..5801daf 100644
--- a/test/power-doctest.test.js
+++ b/test/power-doctest.test.js
@@ -6,7 +6,8 @@ function parseAndConvert(code) {
         range: true,
         comment: true,
         attachComment: true,
-        tokens: true
+        tokens: true,
+        sourceType: 'module'
     };
     var AST = parse(code, options);
     return convertAST(AST);
@@ -22,6 +23,20 @@ describe("power-doctest", function () {
                 var a = 1;
             `);
         });
+        it("module type", function () {
+            var code = `
+export default function hello(){
+    var a = 1;
+}
+            `;
+            var resultAST = parseAndConvert(code);
+            astEqual(resultAST, `
+            var assert = require("power-assert");
+            export default function hello(){
+                var a = 1;
+            }
+            `);
+        });
         it("convert assert to power-assert format", function () {
             var code = `var a = 1;
                             a; // => 1`;