diff --git a/CHANGELOG.md b/CHANGELOG.md
index e707ff2..1422f95 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,8 +3,12 @@
  * @Author: ekibun
  * @Date: 2020-08-08 08:16:50
  * @LastEditors: ekibun
- * @LastEditTime: 2020-10-03 00:28:18
+ * @LastEditTime: 2020-10-03 23:34:30
 -->
+## 0.1.2
+
+* fix qjs memory leak.
+
 ## 0.1.1
 
 * run on isolate.
diff --git a/README.md b/README.md
index cc00f95..afa9418 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@
  * @Author: ekibun
  * @Date: 2020-08-08 08:16:50
  * @LastEditors: ekibun
- * @LastEditTime: 2020-10-03 00:36:36
+ * @LastEditTime: 2020-10-03 00:44:41
 -->
 # flutter_qjs
 
@@ -67,7 +67,7 @@ channel("http", ["http://example.com/"]);
 
 ~~I cannot find a way to convert the sync ffi callback into an async function. So the assets files received by async function `rootBundle.loadString` cannot be used in this version. I will appreciate it if you can provide me a solution to make `ModuleHandler` async.~~
 
-To use async function in module handler, try [Run on isolate thread](#isolate)
+To use async function in module handler, try [Run on isolate thread](#Run-on-isolate-thread)
 
 ```dart
 await engine.setModuleHandler((String module) {
@@ -94,7 +94,7 @@ try {
 
 5. Method `recreate` can destroy quickjs runtime that can be recreated again if you call `evaluate`, `recreat` can be used to reset the module cache. Call `close` to stop `dispatch` when you do not need it.
 
-### <span id="isolate">Run on isolate thread</span>
+### Run on isolate thread
 
 1. Create a `IsolateQjs` object, pass a handler to implement js-dart interaction. The handler is used in isolate, so the function must be a top-level function or a static method.
 
diff --git a/cxx/ffi.cpp b/cxx/ffi.cpp
index b766e1d..af3bf6c 100644
--- a/cxx/ffi.cpp
+++ b/cxx/ffi.cpp
@@ -3,7 +3,7 @@
  * @Author: ekibun
  * @Date: 2020-09-06 18:32:45
  * @LastEditors: ekibun
- * @LastEditTime: 2020-09-24 22:32:15
+ * @LastEditTime: 2020-10-03 23:26:14
  */
 #include "ffi.h"
 #include <functional>
@@ -226,7 +226,7 @@ extern "C"
   }
 
   DLLEXPORT int32_t jsDefinePropertyValue(JSContext *ctx, JSValueConst *this_obj,
-                                      JSAtom prop, JSValue *val, int32_t flags)
+                                          JSAtom prop, JSValue *val, int32_t flags)
   {
     return JS_DefinePropertyValue(ctx, *this_obj, prop, *val, flags);
   }
@@ -247,7 +247,7 @@ extern "C"
   }
 
   DLLEXPORT int32_t jsGetOwnPropertyNames(JSContext *ctx, JSPropertyEnum **ptab,
-                                      uint32_t *plen, JSValueConst *obj, int32_t flags)
+                                          uint32_t *plen, JSValueConst *obj, int32_t flags)
   {
     return JS_GetOwnPropertyNames(ctx, ptab, plen, *obj, flags);
   }
@@ -259,7 +259,7 @@ extern "C"
 
   DLLEXPORT uint32_t sizeOfJSValue()
   {
-    return sizeof (JSValue);
+    return sizeof(JSValue);
   }
 
   DLLEXPORT void setJSValueList(JSValue *list, uint32_t i, JSValue *val)
@@ -293,4 +293,9 @@ extern "C"
   {
     return new JSValue(JS_NewPromiseCapability(ctx, resolving_funcs));
   }
+
+  DLLEXPORT void jsFree(JSContext *ctx, void *ptab)
+  {
+    js_free(ctx, ptab);
+  }
 }
\ No newline at end of file
diff --git a/cxx/ffi.h b/cxx/ffi.h
index 4fdeff8..7f2b299 100644
--- a/cxx/ffi.h
+++ b/cxx/ffi.h
@@ -106,4 +106,6 @@ extern "C"
   DLLEXPORT int32_t jsExecutePendingJob(JSRuntime *rt);
 
   DLLEXPORT JSValue *jsNewPromiseCapability(JSContext *ctx, JSValue *resolving_funcs);
+
+  DLLEXPORT void jsFree(JSContext *ctx, void *ptab);
 }
\ No newline at end of file
diff --git a/example/lib/main.dart b/example/lib/main.dart
index 0228080..7d89ef0 100644
--- a/example/lib/main.dart
+++ b/example/lib/main.dart
@@ -3,7 +3,7 @@
  * @Author: ekibun
  * @Date: 2020-08-08 08:16:51
  * @LastEditors: ekibun
- * @LastEditTime: 2020-10-03 00:38:41
+ * @LastEditTime: 2020-10-03 21:37:22
  */
 import 'package:flutter/material.dart';
 import 'dart:typed_data';
@@ -103,8 +103,8 @@ class _TestPageState extends State<TestPage> {
                       onPressed: () async {
                         _ensureEngine();
                         try {
-                          resp = (await engine.evaluate(
-                                  _controller.text ?? '', "<eval>"))
+                          resp = (await engine.evaluate(_controller.text ?? '',
+                                  name: "<eval>"))
                               .toString();
                         } catch (e) {
                           resp = e.toString();
diff --git a/example/pubspec.lock b/example/pubspec.lock
index b017748..312ef0c 100644
--- a/example/pubspec.lock
+++ b/example/pubspec.lock
@@ -7,42 +7,42 @@ packages:
       name: async
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.5.0-nullsafety"
+    version: "2.5.0-nullsafety.1"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.1.0-nullsafety"
+    version: "2.1.0-nullsafety.1"
   characters:
     dependency: transitive
     description:
       name: characters
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.0-nullsafety.2"
+    version: "1.1.0-nullsafety.3"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.2.0-nullsafety"
+    version: "1.2.0-nullsafety.1"
   clock:
     dependency: transitive
     description:
       name: clock
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.0-nullsafety"
+    version: "1.1.0-nullsafety.1"
   collection:
     dependency: transitive
     description:
       name: collection
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.15.0-nullsafety.2"
+    version: "1.15.0-nullsafety.3"
   dio:
     dependency: "direct main"
     description:
@@ -56,7 +56,7 @@ packages:
       name: fake_async
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.0-nullsafety"
+    version: "1.2.0-nullsafety.1"
   ffi:
     dependency: transitive
     description:
@@ -82,7 +82,7 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "0.1.1"
+    version: "0.1.2"
   flutter_test:
     dependency: "direct dev"
     description: flutter
@@ -108,21 +108,21 @@ packages:
       name: matcher
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.12.10-nullsafety"
+    version: "0.12.10-nullsafety.1"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.3.0-nullsafety.2"
+    version: "1.3.0-nullsafety.3"
   path:
     dependency: transitive
     description:
       name: path
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.8.0-nullsafety"
+    version: "1.8.0-nullsafety.1"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -134,56 +134,56 @@ packages:
       name: source_span
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.8.0-nullsafety"
+    version: "1.8.0-nullsafety.2"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.10.0-nullsafety"
+    version: "1.10.0-nullsafety.2"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.1.0-nullsafety"
+    version: "2.1.0-nullsafety.1"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.0-nullsafety"
+    version: "1.1.0-nullsafety.1"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.2.0-nullsafety"
+    version: "1.2.0-nullsafety.1"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.2.19-nullsafety"
+    version: "0.2.19-nullsafety.2"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.3.0-nullsafety.2"
+    version: "1.3.0-nullsafety.3"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.1.0-nullsafety.2"
+    version: "2.1.0-nullsafety.3"
 sdks:
-  dart: ">=2.10.0-0.0.dev <2.10.0"
+  dart: ">=2.10.0-110 <=2.11.0-181.0.dev"
   flutter: ">=1.20.0 <2.0.0"
diff --git a/lib/ffi.dart b/lib/ffi.dart
index 7b15966..89677fb 100644
--- a/lib/ffi.dart
+++ b/lib/ffi.dart
@@ -3,7 +3,7 @@
  * @Author: ekibun
  * @Date: 2020-09-19 10:29:04
  * @LastEditors: ekibun
- * @LastEditTime: 2020-09-27 01:12:16
+ * @LastEditTime: 2020-10-03 23:27:15
  */
 import 'dart:ffi';
 import 'dart:io';
@@ -744,3 +744,16 @@ final Pointer Function(
       Pointer,
     )>>("jsNewPromiseCapability")
     .asFunction();
+
+/// void jsFree(JSContext *ctx, void *ptab)
+final void Function(
+  Pointer ctx,
+  Pointer ptab,
+) jsFree = qjsLib
+    .lookup<
+        NativeFunction<
+            Void Function(
+      Pointer,
+      Pointer,
+    )>>("jsFree")
+    .asFunction();
diff --git a/lib/flutter_qjs.dart b/lib/flutter_qjs.dart
index 4af1c82..ddc0ac8 100644
--- a/lib/flutter_qjs.dart
+++ b/lib/flutter_qjs.dart
@@ -3,7 +3,7 @@
  * @Author: ekibun
  * @Date: 2020-08-08 08:29:09
  * @LastEditors: ekibun
- * @LastEditTime: 2020-10-03 00:18:49
+ * @LastEditTime: 2020-10-03 21:55:07
  */
 import 'dart:async';
 import 'dart:ffi';
@@ -116,9 +116,10 @@ class FlutterQjs {
   }
 
   /// Evaluate js script.
-  Future<dynamic> evaluate(String command, String name) async {
+  Future<dynamic> evaluate(String command, {String name, int evalFlags}) async {
     _ensureEngine();
-    var jsval = jsEval(_ctx, command, name, JSEvalType.GLOBAL);
+    var jsval =
+        jsEval(_ctx, command, name ?? "<eval>", evalFlags ?? JSEvalType.GLOBAL);
     if (jsIsException(jsval) != 0) {
       throw Exception(parseJSException(_ctx));
     }
diff --git a/lib/isolate.dart b/lib/isolate.dart
index 38cc760..3b7459d 100644
--- a/lib/isolate.dart
+++ b/lib/isolate.dart
@@ -3,7 +3,7 @@
  * @Author: ekibun
  * @Date: 2020-10-02 13:49:03
  * @LastEditors: ekibun
- * @LastEditTime: 2020-10-03 00:18:40
+ * @LastEditTime: 2020-10-03 22:21:31
  */
 import 'dart:async';
 import 'dart:ffi';
@@ -123,18 +123,21 @@ void _runJsIsolate(Map spawnMessage) async {
   sendPort.send(port.sendPort);
   qjs.setMethodHandler(methodHandler);
   qjs.setModuleHandler((name) {
-    var ptr = allocate<Int64>();
+    var ptr = allocate<Pointer<Utf8>>();
+    ptr.value = Pointer.fromAddress(0);
     sendPort.send({
       'type': 'module',
       'name': name,
       'ptr': ptr.address,
     });
-    ptr.value = 0;
-    while (ptr.value == 0) sleep(Duration.zero);
-    print(ptr.value);
-    if (ptr.value == -1) throw Exception("Module Not found");
-    var strptr = Pointer<Utf8>.fromAddress(ptr.value);
-    var ret = Utf8.fromUtf8(strptr);
+    while (ptr.value.address == 0) sleep(Duration.zero);
+    if (ptr.value.address == -1) throw Exception("Module Not found");
+    var ret = Utf8.fromUtf8(ptr.value);
+    sendPort.send({
+      'type': 'release',
+      'ptr': ptr.value.address,
+    });
+    free(ptr);
     return ret;
   });
   qjs.dispatch();
@@ -144,7 +147,11 @@ void _runJsIsolate(Map spawnMessage) async {
     try {
       switch (msg['type']) {
         case 'evaluate':
-          data = await qjs.evaluate(msg['command'], msg['name']);
+          data = await qjs.evaluate(
+            msg['command'],
+            name: msg['name'],
+            evalFlags: msg['flag'],
+          );
           break;
         case 'call':
           data = JSFunction.fromAddress(
@@ -174,7 +181,7 @@ typedef JsAsyncModuleHandler = Future<String> Function(String name);
 typedef JsIsolateSpawn = void Function(SendPort sendPort);
 
 class IsolateQjs {
-  SendPort _sendPort;
+  Future<SendPort> _sendPort;
   JsMethodHandler _methodHandler;
   JsAsyncModuleHandler _moduleHandler;
 
@@ -182,7 +189,7 @@ class IsolateQjs {
   /// The function must be a top-level function or a static method
   IsolateQjs(this._methodHandler);
 
-  Future<void> _ensureEngine() async {
+  _ensureEngine() {
     if (_sendPort != null) return;
     ReceivePort port = ReceivePort();
     Isolate.spawn(
@@ -193,28 +200,30 @@ class IsolateQjs {
       },
       errorsAreFatal: true,
     );
-    var completer = Completer();
+    var completer = Completer<SendPort>();
     port.listen((msg) async {
       if (msg is SendPort && !completer.isCompleted) {
-        _sendPort = msg;
-        completer.complete();
+        completer.complete(msg);
         return;
       }
       switch (msg['type']) {
         case 'module':
-          var ptr = Pointer<Int64>.fromAddress(msg['ptr']);
+          var ptr = Pointer<Pointer>.fromAddress(msg['ptr']);
           try {
-            ptr.value = Utf8.toUtf8(await _moduleHandler(msg['name'])).address;
+            ptr.value = Utf8.toUtf8(await _moduleHandler(msg['name']));
           } catch (e) {
-            ptr.value = -1;
+            ptr.value = Pointer.fromAddress(-1);
           }
           break;
+        case 'release':
+          free(Pointer.fromAddress(msg['ptr']));
+          break;
       }
     }, onDone: () {
       close();
       if (!completer.isCompleted) completer.completeError('isolate close');
     });
-    await completer.future;
+    _sendPort = completer.future;
   }
 
   /// Set a handler to manage js module.
@@ -223,24 +232,29 @@ class IsolateQjs {
   }
 
   close() {
-    _sendPort.send({
-      'type': 'close',
+    if (_sendPort == null) return;
+    _sendPort.then((sendPort) {
+      sendPort.send({
+        'type': 'close',
+      });
     });
     _sendPort = null;
   }
 
-  Future<dynamic> evaluate(String command, String name) async {
-    await _ensureEngine();
+  Future<dynamic> evaluate(String command, {String name, int evalFlags}) async {
+    _ensureEngine();
     var evaluatePort = ReceivePort();
-    _sendPort.send({
+    var sendPort = await _sendPort;
+    sendPort.send({
       'type': 'evaluate',
       'command': command,
       'name': name,
+      'flag': evalFlags,
       'port': evaluatePort.sendPort,
     });
     var result = await evaluatePort.first;
     if (result['data'] != null)
-      return _decodeData(result['data'], _sendPort);
+      return _decodeData(result['data'], sendPort);
     else
       throw result['error'];
   }
diff --git a/lib/wrapper.dart b/lib/wrapper.dart
index 1a98f8d..923b1d1 100644
--- a/lib/wrapper.dart
+++ b/lib/wrapper.dart
@@ -3,7 +3,7 @@
  * @Author: ekibun
  * @Date: 2020-09-19 22:07:47
  * @LastEditors: ekibun
- * @LastEditTime: 2020-10-02 16:37:16
+ * @LastEditTime: 2020-10-03 23:27:36
  */
 import 'dart:async';
 import 'dart:ffi';
@@ -84,11 +84,12 @@ class JSFunction extends JSRefValue {
       jsFreeValue(ctx, jsArg);
     }
     bool isException = jsIsException(jsRet) != 0;
-    var ret = jsToDart(ctx, jsRet);
-    jsFreeValue(ctx, jsRet);
     if (isException) {
+      jsFreeValue(ctx, jsRet);
       throw Exception(parseJSException(ctx));
     }
+    var ret = jsToDart(ctx, jsRet);
+    jsFreeValue(ctx, jsRet);
     return ret;
   }
 
@@ -257,6 +258,7 @@ dynamic jsToDart(Pointer ctx, Pointer val, {Map<int, dynamic> cache}) {
           jsFreeValue(ctx, jsProp);
           jsFreeAtom(ctx, jsAtom);
         }
+        jsFree(ctx, ptab.value);
         free(ptab);
         return ret;
       }
diff --git a/pubspec.lock b/pubspec.lock
index b68689c..65c7e4f 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -7,49 +7,49 @@ packages:
       name: async
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.5.0-nullsafety"
+    version: "2.5.0-nullsafety.1"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.1.0-nullsafety"
+    version: "2.1.0-nullsafety.1"
   characters:
     dependency: transitive
     description:
       name: characters
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.0-nullsafety.2"
+    version: "1.1.0-nullsafety.3"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.2.0-nullsafety"
+    version: "1.2.0-nullsafety.1"
   clock:
     dependency: transitive
     description:
       name: clock
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.0-nullsafety"
+    version: "1.1.0-nullsafety.1"
   collection:
     dependency: transitive
     description:
       name: collection
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.15.0-nullsafety.2"
+    version: "1.15.0-nullsafety.3"
   fake_async:
     dependency: transitive
     description:
       name: fake_async
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.0-nullsafety"
+    version: "1.2.0-nullsafety.1"
   ffi:
     dependency: "direct main"
     description:
@@ -73,21 +73,21 @@ packages:
       name: matcher
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.12.10-nullsafety"
+    version: "0.12.10-nullsafety.1"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.3.0-nullsafety.2"
+    version: "1.3.0-nullsafety.3"
   path:
     dependency: transitive
     description:
       name: path
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.8.0-nullsafety"
+    version: "1.8.0-nullsafety.1"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -99,56 +99,56 @@ packages:
       name: source_span
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.8.0-nullsafety"
+    version: "1.8.0-nullsafety.2"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.10.0-nullsafety"
+    version: "1.10.0-nullsafety.2"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.1.0-nullsafety"
+    version: "2.1.0-nullsafety.1"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.0-nullsafety"
+    version: "1.1.0-nullsafety.1"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.2.0-nullsafety"
+    version: "1.2.0-nullsafety.1"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.2.19-nullsafety"
+    version: "0.2.19-nullsafety.2"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.3.0-nullsafety.2"
+    version: "1.3.0-nullsafety.3"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.1.0-nullsafety.2"
+    version: "2.1.0-nullsafety.3"
 sdks:
-  dart: ">=2.10.0-0.0.dev <2.10.0"
+  dart: ">=2.10.0-110 <=2.11.0-181.0.dev"
   flutter: ">=1.20.0 <2.0.0"
diff --git a/pubspec.yaml b/pubspec.yaml
index be064db..0537289 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: flutter_qjs
 description: This plugin is a simple js engine for flutter using the `quickjs` project. Plugin currently supports all the platforms except web!
-version: 0.1.1
+version: 0.1.2
 homepage: https://github.com/ekibun/flutter_qjs
 
 environment:
diff --git a/test/flutter_qjs_test.dart b/test/flutter_qjs_test.dart
index ebeb76f..ef72181 100644
--- a/test/flutter_qjs_test.dart
+++ b/test/flutter_qjs_test.dart
@@ -3,7 +3,7 @@
  * @Author: ekibun
  * @Date: 2020-09-06 13:02:46
  * @LastEditors: ekibun
- * @LastEditTime: 2020-10-02 17:27:52
+ * @LastEditTime: 2020-10-03 21:36:06
  */
 import 'dart:convert';
 import 'dart:io';
@@ -67,7 +67,7 @@ void main() async {
           (...args)=>`hello \${args}!`, a,
           0.1, true, false, 1, "world", module
         ]));
-      """, "<eval>");
+      """, name: "<eval>");
     print(value);
     print(await value[0]('world'));
     qjs.close();