diff --git a/Makefile b/Makefile
index 91c5ecf5..e4782090 100644
--- a/Makefile
+++ b/Makefile
@@ -64,7 +64,7 @@ build/program.jar.js: program.jar build/jsc.js aot-methods.txt
 	js build/jsc.js -cp java/classes.jar program.jar -d -jf program.jar -mff aot-methods.txt > build/program.jar.js
 
 closure: build/classes.jar.js build/j2me.js
-	java -jar tools/closure.jar --language_in ECMASCRIPT5 -O SHUMWAY_OPTIMIZATIONS build/j2me.js > build/j2me.cc.js \
+	java -jar tools/closure.jar --language_in ECMASCRIPT5 -O J2ME_OPTIMIZATIONS build/j2me.js > build/j2me.cc.js \
 		&& mv build/j2me.cc.js build/j2me.js
 	java -jar tools/closure.jar --language_in ECMASCRIPT5 -O SIMPLE build/classes.jar.js > build/classes.jar.cc.js \
 		&& mv build/classes.jar.cc.js build/classes.jar.js
diff --git a/README.md b/README.md
index 9af221ac..596748c2 100644
--- a/README.md
+++ b/README.md
@@ -205,8 +205,8 @@ To use it, first install a recent version of the
 
 `make closure` compiles some JavaScript code with the Closure compiler.
 
-To use it, first download Shumway's version of the compiler to tools/closure.jar:
+To use it, first download this custom version of the compiler to tools/closure.jar:
 
 ```
-wget https://github.com/mozilla/shumway/raw/master/utils/closure.jar -P tools/
+wget https://github.com/mykmelez/closure-compiler/releases/download/v0.1/closure.jar -P tools/
 ```
diff --git a/jit/analyze.ts b/jit/analyze.ts
index 4ad1e9b6..3125e7a9 100644
--- a/jit/analyze.ts
+++ b/jit/analyze.ts
@@ -32,10 +32,7 @@ module J2ME {
     "com/sun/midp/util/isolate/InterIsolateMutex.lock0.(I)V": YieldReason.Root,
     "com/sun/midp/events/NativeEventMonitor.waitForNativeEvent.(Lcom/sun/midp/events/NativeEvent;)I": YieldReason.Root,
     "com/sun/midp/io/j2me/push/ConnectionRegistry.poll0.(J)I": YieldReason.Root,
-    "com/sun/midp/rms/RecordStoreUtil.exists.(Ljava/lang/String;Ljava/lang/String;I)Z": YieldReason.Root,
     "com/sun/midp/rms/RecordStoreFile.openRecordStoreFile.(Ljava/lang/String;Ljava/lang/String;I)I": YieldReason.Root,
-    "com/sun/midp/rms/RecordStoreFile.commitWrite.(I)V": YieldReason.Root,
-    "com/sun/midp/rms/RecordStoreFile.closeFile.(I)V": YieldReason.Root,
     "com/ibm/oti/connection/file/Connection.truncateImpl.([BJ)V": YieldReason.Root,
     "com/ibm/oti/connection/file/FCInputStream.openImpl.([B)I": YieldReason.Root,
     "com/ibm/oti/connection/file/FCOutputStream.openImpl.([B)I": YieldReason.Root,
diff --git a/libs/fs.js b/libs/fs.js
index 676b45ec..021c26a4 100644
--- a/libs/fs.js
+++ b/libs/fs.js
@@ -383,7 +383,7 @@ var fs = (function() {
       }
     }
 
-    var newArray = new Uint8Array(newBufferSize);
+    var newArray = new Int8Array(newBufferSize);
     newArray.set(this.array);
 
     this.array = newArray;
@@ -463,7 +463,7 @@ var fs = (function() {
         var fd = openedFiles.push({
           dirty: false,
           path: path,
-          buffer: new FileBuffer(new Uint8Array(reader.result)),
+          buffer: new FileBuffer(new Int8Array(reader.result)),
           mtime: record.mtime,
           size: record.size,
           position: 0,
diff --git a/midp/codec.js b/midp/codec.js
index 4228e51b..735ff70e 100644
--- a/midp/codec.js
+++ b/midp/codec.js
@@ -66,7 +66,7 @@ DataEncoder.prototype.getData = function() {
 }
 
 var DataDecoder = function(data, offset, length) {
-  this.data = JSON.parse(util.decodeUtf8(new Uint8Array(data.buffer, offset, length)));
+  this.data = JSON.parse(util.decodeUtf8(new Int8Array(data.buffer, offset, length)));
   this.current = [];
 }
 
diff --git a/midp/crypto.js b/midp/crypto.js
index 11f8e0cc..95916e18 100644
--- a/midp/crypto.js
+++ b/midp/crypto.js
@@ -99,7 +99,7 @@ Native["com/sun/midp/crypto/SHA.nativeFinal.([BII[BI[I[I[I[I)V"] = function(inBu
     }
 
     var hash = hasher.digest();
-    outBuf.set(new Uint8Array(hash.buffer), outOff);
+    outBuf.set(new Int8Array(hash.buffer), outOff);
 
     // XXX Call the reset method instead to completely reset the object.
     data.set(MIDP.emptyDataArray);
@@ -120,7 +120,7 @@ Native["com/sun/midp/crypto/SHA.nativeClone.([I)V"] = function(data) {
 };
 
 Native["com/sun/midp/crypto/MD5.nativeUpdate.([BII[I[I[I[I)V"] = function(inBuf, inOff, inLen, state, num, count, data) {
-    MIDP.getMD5Hasher(data).update(MIDP.bin2String(new Uint8Array(inBuf.subarray(inOff, inOff + inLen))));
+    MIDP.getMD5Hasher(data).update(MIDP.bin2String(new Int8Array(inBuf.subarray(inOff, inOff + inLen))));
 };
 
 Native["com/sun/midp/crypto/MD5.nativeFinal.([BII[BI[I[I[I[I)V"] = function(inBuf, inOff, inLen, outBuf, outOff, state, num, count, data) {
diff --git a/midp/fs.js b/midp/fs.js
index 8845ccee..26191b1b 100644
--- a/midp/fs.js
+++ b/midp/fs.js
@@ -38,11 +38,8 @@ Native["com/sun/midp/midletsuite/MIDletSuiteStorage.getSecureFilenameBase.(I)Lja
 
 Native["com/sun/midp/rms/RecordStoreUtil.exists.(Ljava/lang/String;Ljava/lang/String;I)Z"] =
 function(filenameBase, name, ext) {
-    asyncImpl("Z", new Promise(function(resolve, reject) {
-        var path = RECORD_STORE_BASE + "/" + util.fromJavaString(filenameBase) + "/" + util.fromJavaString(name) + "." + ext;
-        // return fs.exists(path) ? 1 : 0;
-        resolve(fs.exists(path) ? 1 : 0);
-    }));
+    var path = RECORD_STORE_BASE + "/" + util.fromJavaString(filenameBase) + "/" + util.fromJavaString(name) + "." + ext;
+    return fs.exists(path) ? 1 : 0;
 };
 
 Native["com/sun/midp/rms/RecordStoreUtil.deleteFile.(Ljava/lang/String;Ljava/lang/String;I)V"] =
@@ -134,17 +131,11 @@ Native["com/sun/midp/rms/RecordStoreFile.writeBytes.(I[BII)V"] = function(handle
 };
 
 Native["com/sun/midp/rms/RecordStoreFile.commitWrite.(I)V"] = function(handle) {
-    asyncImpl("V", new Promise(function(resolve, reject) {
-        fs.flush(handle);
-        resolve();
-    }));
+    fs.flush(handle);
 };
 
 Native["com/sun/midp/rms/RecordStoreFile.closeFile.(I)V"] = function(handle) {
-    asyncImpl("V", new Promise(function(resolve, reject) {
-        fs.close(handle);
-        resolve();
-    }));
+    fs.close(handle);
 };
 
 Native["com/sun/midp/rms/RecordStoreFile.truncateFile.(II)V"] = function(handle, size) {
@@ -493,7 +484,7 @@ Native["com/ibm/oti/connection/file/FCInputStream.readByteImpl.(I)I"] = function
 
     var data = fs.read(fd, curpos, curpos+1);
 
-    return (data.byteLength > 0) ? data[0] : -1;
+    return (data.byteLength > 0) ? (data[0] & 0xFF) : -1;
 };
 
 Native["com/ibm/oti/connection/file/FCInputStream.closeImpl.(I)V"] = function(fd) {
@@ -551,7 +542,7 @@ Native["com/ibm/oti/connection/file/FCOutputStream.syncImpl.(I)V"] = function(fd
 };
 
 Native["com/ibm/oti/connection/file/FCOutputStream.writeByteImpl.(II)V"] = function(val, fd) {
-    var buf = new Uint8Array(1);
+    var buf = new Int8Array(1);
     buf[0] = val;
     fs.write(fd, buf);
 };
diff --git a/midp/localmsg.js b/midp/localmsg.js
index 0733a11c..37aba1ea 100644
--- a/midp/localmsg.js
+++ b/midp/localmsg.js
@@ -174,7 +174,7 @@ NokiaMessagingLocalMsgConnection.prototype.sendMessageToServer = function(messag
 
     default:
       console.error("(nokia.messaging) event " + name + " not implemented " +
-                    util.decodeUtf8(new Uint8Array(message.data.buffer, message.offset, message.length)));
+                    util.decodeUtf8(new Int8Array(message.data.buffer, message.offset, message.length)));
       return;
   }
 
@@ -381,7 +381,7 @@ NokiaPhoneStatusLocalMsgConnection.prototype.sendMessageToServer = function(mess
 
             default:
               console.error("(nokia.phone-status) Query " + decoder.getName() + " not implemented " +
-                            util.decodeUtf8(new Uint8Array(message.data.buffer, message.offset, message.length)));
+                            util.decodeUtf8(new Int8Array(message.data.buffer, message.offset, message.length)));
               break;
           }
         } else if (queryKind === "Disable") {
@@ -407,7 +407,7 @@ NokiaPhoneStatusLocalMsgConnection.prototype.sendMessageToServer = function(mess
 
     default:
       console.error("(nokia.phone-status) event " + name + " not implemented " +
-                    util.decodeUtf8(new Uint8Array(message.data.buffer, message.offset, message.length)));
+                    util.decodeUtf8(new Int8Array(message.data.buffer, message.offset, message.length)));
       return;
   }
 };
@@ -526,7 +526,7 @@ NokiaContactsLocalMsgConnection.prototype.sendMessageToServer = function(message
       var numEntries = decoder.getValue(DataType.ULONG);
       if (numEntries !== 1) {
         console.error("(nokia.contacts) event getFirst with numEntries != 1 not implemented " +
-                      util.decodeUtf8(new Uint8Array(message.data.buffer, message.offset, message.length)));
+                      util.decodeUtf8(new Int8Array(message.data.buffer, message.offset, message.length)));
       }
 
       this.getFirstOrNext(trans_id, "getFirst");
@@ -542,12 +542,12 @@ NokiaContactsLocalMsgConnection.prototype.sendMessageToServer = function(message
       var includeStartEntry = decoder.getValue(DataType.BOOLEAN);
       if (includeStartEntry == 1) {
         console.error("(nokia.contacts) event getNext with includeStartEntry == true not implemented " +
-                      util.decodeUtf8(new Uint8Array(message.data.buffer, message.offset, message.length)));
+                      util.decodeUtf8(new Int8Array(message.data.buffer, message.offset, message.length)));
       }
       var numEntries = decoder.getValue(DataType.ULONG);
       if (numEntries !== 1) {
         console.error("(nokia.contacts) event getNext with numEntries != 1 not implemented " +
-                      util.decodeUtf8(new Uint8Array(message.data.buffer, message.offset, message.length)));
+                      util.decodeUtf8(new Int8Array(message.data.buffer, message.offset, message.length)));
       }
 
       this.getFirstOrNext(trans_id, "getNext");
@@ -555,7 +555,7 @@ NokiaContactsLocalMsgConnection.prototype.sendMessageToServer = function(message
 
     default:
       console.error("(nokia.contacts) event " + name + " not implemented " +
-                    util.decodeUtf8(new Uint8Array(message.data.buffer, message.offset, message.length)));
+                    util.decodeUtf8(new Int8Array(message.data.buffer, message.offset, message.length)));
       return;
   }
 }
@@ -684,7 +684,7 @@ NokiaFileUILocalMsgConnection.prototype.sendMessageToServer = function(message)
 
     default:
       console.error("(nokia.file-ui) event " + name + " not implemented " +
-                    util.decodeUtf8(new Uint8Array(message.data.buffer, message.offset, message.length)));
+                    util.decodeUtf8(new Int8Array(message.data.buffer, message.offset, message.length)));
       return;
   }
 };
@@ -756,7 +756,7 @@ NokiaImageProcessingLocalMsgConnection.prototype.sendMessageToServer = function(
 
       if (aspect != "FullImage" && aspect != "LockToPartialView") {
         console.error("(nokia.image-processing) event " + name + " with aspect != 'FullImage' or 'LockToPartialView' not implemented " +
-                      util.decodeUtf8(new Uint8Array(message.data.buffer, message.offset, message.length)));
+                      util.decodeUtf8(new Int8Array(message.data.buffer, message.offset, message.length)));
         return;
       }
 
@@ -859,7 +859,7 @@ NokiaImageProcessingLocalMsgConnection.prototype.sendMessageToServer = function(
 
     default:
       console.error("(nokia.image-processing) event " + name + " not implemented " +
-                    util.decodeUtf8(new Uint8Array(message.data.buffer, message.offset, message.length)));
+                    util.decodeUtf8(new Int8Array(message.data.buffer, message.offset, message.length)));
       return;
   }
 };
@@ -913,7 +913,7 @@ NokiaProductInfoLocalMsgConnection.prototype.sendMessageToServer = function(mess
       break;
     default:
       console.error("(nokia.status-info) event " + name + " not implemented " +
-                    util.decodeUtf8(new Uint8Array(message.data.buffer, message.offset, message.length)));
+                    util.decodeUtf8(new Int8Array(message.data.buffer, message.offset, message.length)));
       return;
   }
 };
@@ -1038,7 +1038,7 @@ NokiaActiveStandbyLocalMsgConnection.prototype.sendMessageToServer = function(me
 
     default:
       console.error("(nokia.active-standby) event " + name + " not implemented " +
-                    util.decodeUtf8(new Uint8Array(message.data.buffer, message.offset, message.length)));
+                    util.decodeUtf8(new Int8Array(message.data.buffer, message.offset, message.length)));
       return;
   }
 }
@@ -1124,7 +1124,7 @@ Native["org/mozilla/io/LocalMsgConnection.sendData.([BII)V"] = function(data, of
         this.connection.sendMessageToClient(message);
     } else {
         if (MIDP.FakeLocalMsgServers.indexOf(this.protocolName) != -1) {
-            console.warn("sendData (" + util.decodeUtf8(new Uint8Array(data.buffer, offset, length)) + ") to an unimplemented localmsg server (" + this.protocolName + ")");
+            console.warn("sendData (" + util.decodeUtf8(new Int8Array(data.buffer, offset, length)) + ") to an unimplemented localmsg server (" + this.protocolName + ")");
         }
 
         this.connection.sendMessageToServer(message);
diff --git a/midp/media.js b/midp/media.js
index 91e858ea..aba269d1 100644
--- a/midp/media.js
+++ b/midp/media.js
@@ -714,7 +714,7 @@ PlayerContainer.prototype.getRecordedSize = function() {
 PlayerContainer.prototype.getRecordedData = function(offset, size, buffer) {
     var toRead = (size < this.audioRecorder.data.length) ? size : this.audioRecorder.data.byteLength;
     buffer.set(this.audioRecorder.data.subarray(0, toRead), offset);
-    this.audioRecorder.data = new Uint8Array(this.audioRecorder.data.buffer.slice(toRead));
+    this.audioRecorder.data = new Int8Array(this.audioRecorder.data.buffer.slice(toRead));
 };
 
 PlayerContainer.prototype.startSnapshot = function(imageType) {
@@ -732,7 +732,7 @@ PlayerContainer.prototype.getDuration = function() {
 var AudioRecorder = function(aMimeType) {
     this.mimeType = aMimeType || "audio/3gpp";
     this.eventListeners = {};
-    this.data = new Uint8Array();
+    this.data = new Int8Array();
     this.sender = DumbPipe.open("audiorecorder", {
         mimeType: this.mimeType
     }, this.recipient.bind(this));
@@ -816,7 +816,7 @@ AudioRecorder.prototype.stop = function() {
             // The audio data we received are encoded with a proper format, it doesn't
             // make sense to concatenate them like the socket, so let just override
             // the buffered data here.
-            var data = new Uint8Array(message.data);
+            var data = new Int8Array(message.data);
             if (this.getContentType() === "audio/amr") {
                 data = Media.convert3gpToAmr(data);
             }
@@ -854,7 +854,7 @@ AudioRecorder.prototype.pause = function() {
             // The audio data we received are encoded with a proper format, it doesn't
             // make sense to concatenate them like the socket, so let just override
             // the buffered data here.
-            this.data = new Uint8Array(message.data);
+            this.data = new Int8Array(message.data);
             resolve(1);
         }.bind(this);
 
diff --git a/midp/midp.js b/midp/midp.js
index a9f93f10..8b73e555 100644
--- a/midp/midp.js
+++ b/midp/midp.js
@@ -97,7 +97,7 @@ Native["com/sun/midp/jarutil/JarReader.readJarEntry0.(Ljava/lang/String;Ljava/la
     if (!bytes)
         throw $.newIOException();
     var length = bytes.byteLength;
-    var data = new Uint8Array(bytes);
+    var data = new Int8Array(bytes);
     var array = J2ME.newByteArray(length);
     for (var n = 0; n < length; ++n)
         array[n] = data[n];
@@ -535,7 +535,7 @@ Native["com/sun/midp/util/ResourceHandler.loadRomizedResource0.(Ljava/lang/Strin
     }
     var len = data.byteLength;
     var bytes = J2ME.newByteArray(len);
-    var src = new Uint8Array(data);
+    var src = new Int8Array(data);
     for (var n = 0; n < bytes.byteLength; ++n)
         bytes[n] = src[n];
     return bytes;
@@ -862,33 +862,29 @@ Native["com/sun/midp/util/isolate/InterIsolateMutex.getID0.(Ljava/lang/String;)I
 
 Native["com/sun/midp/util/isolate/InterIsolateMutex.lock0.(I)V"] = function(id) {
     var ctx = $.ctx;
+    var mutex;
+    for (var i = 0; i < MIDP.InterIsolateMutexes.length; i++) {
+        if (MIDP.InterIsolateMutexes[i].id == id) {
+            mutex = MIDP.InterIsolateMutexes[i];
+            break;
+        }
+    }
+
+    if (!mutex) {
+        throw $.newIllegalStateException("Invalid mutex ID");
+    }
+
+    if (!mutex.locked) {
+        mutex.locked = true;
+        mutex.holder = ctx.runtime.isolate.id;
+        return;
+    }
+
+    if (mutex.holder == ctx.runtime.isolate.id) {
+        throw $.newRuntimeException("Attempting to lock mutex twice within the same Isolate");
+    }
+
     asyncImpl("V", new Promise(function(resolve, reject) {
-        ctx.setAsCurrentContext();
-        var mutex;
-        for (var i = 0; i < MIDP.InterIsolateMutexes.length; i++) {
-            if (MIDP.InterIsolateMutexes[i].id == id) {
-                mutex = MIDP.InterIsolateMutexes[i];
-                break;
-            }
-        }
-
-        if (!mutex) {
-            reject($.newIllegalStateException("Invalid mutex ID"));
-            return;
-        }
-
-        if (!mutex.locked) {
-            mutex.locked = true;
-            mutex.holder = ctx.runtime.isolate.id;
-            resolve();
-            return;
-        }
-
-        if (mutex.holder == ctx.runtime.isolate.id) {
-            reject($.newRuntimeException("Attempting to lock mutex twice within the same Isolate"));
-            return;
-        }
-
         mutex.waiting.push(function() {
             mutex.locked = true;
             mutex.holder = ctx.runtime.isolate.id;
diff --git a/midp/socket.js b/midp/socket.js
index d558e8b0..60196c9f 100644
--- a/midp/socket.js
+++ b/midp/socket.js
@@ -65,7 +65,7 @@ Native["com/sun/midp/io/j2me/socket/Protocol.open0.([BI)V"] = function(ipBytes,
         this.options[SOCKET_OPT.RCVBUF] = 8192;
         this.options[SOCKET_OPT.SNDBUF] = 8192;
 
-        this.data = new Uint8Array();
+        this.data = new Int8Array();
         this.waitingData = null;
 
         this.socket.onopen = function() {
@@ -88,11 +88,11 @@ Native["com/sun/midp/io/j2me/socket/Protocol.open0.([BI)V"] = function(ipBytes,
         this.socket.ondata = (function(message) {
             // console.log("this.socket.ondata: " + JSON.stringify(message));
             if (this.data.byteLength === 0) {
-                this.data = new Uint8Array(message.data);
+                this.data = new Int8Array(message.data);
             } else {
-                var newArray = new Uint8Array(this.data.byteLength + message.data.byteLength);
+                var newArray = new Int8Array(this.data.byteLength + message.data.byteLength);
                 newArray.set(this.data);
-                newArray.set(new Uint8Array(message.data), this.data.byteLength);
+                newArray.set(new Int8Array(message.data), this.data.byteLength);
                 this.data = newArray;
             }
 
diff --git a/native.js b/native.js
index e96a4685..ba59af19 100644
--- a/native.js
+++ b/native.js
@@ -280,13 +280,6 @@ Native["java/lang/Object.getClass.()Ljava/lang/Class;"] = function() {
     return J2ME.getRuntimeKlass($.ctx.runtime, this.klass).classObject;
 };
 
-Native["java/lang/Object.hashCode.()I"] = function() {
-    var hashCode = this.hashCode;
-    while (!hashCode)
-        hashCode = this.hashCode = util.id();
-    return hashCode;
-};
-
 Native["java/lang/Object.wait.(J)V"] = function(timeout) {
     $.ctx.wait(this, timeout.toNumber());
 };
@@ -797,7 +790,7 @@ Native["com/sun/cldc/i18n/j2me/UTF_8_Reader.readNative.([CII)I"] = function(cbuf
 };
 
 Native["java/io/DataInputStream.bytesToUTF.([B)Ljava/lang/String;"] = function(bytearr) {
-    var array = new Uint8Array(bytearr.buffer);
+    var array = new Int8Array(bytearr.buffer);
     try {
         return J2ME.newString(util.decodeUtf8Array(array));
     } catch(e) {
@@ -860,7 +853,7 @@ Native["com/sun/cldc/i18n/j2me/UTF_8_Writer.encodeUTF8.([CII)[B"] = function(cbu
   var count = 0;
 
   while (count < len) {
-    var outputByte = new Uint8Array(4);     // Never more than 4 encoded bytes
+    var outputByte = new Int8Array(4);     // Never more than 4 encoded bytes
     inputChar = 0xffff & cbuf[off + count];
     if (0 != pendingSurrogate) {
       if (0xdc00 <= inputChar && inputChar <= 0xdfff) {
diff --git a/tests/automation.js b/tests/automation.js
index e82570ab..b3def76e 100644
--- a/tests/automation.js
+++ b/tests/automation.js
@@ -70,7 +70,7 @@ var gfxTests = [
 ];
 
 var expectedUnitTestResults = [
-  { name: "pass", number: 71575 },
+  { name: "pass", number: 71574 },
   { name: "fail", number: 0 },
   { name: "known fail", number: 215 },
   { name: "unknown pass", number: 0 }
diff --git a/tests/com/sun/midp/publickeystore/TestInputOutputStorage.java b/tests/com/sun/midp/publickeystore/TestInputOutputStorage.java
index 8ea00257..f408e209 100644
--- a/tests/com/sun/midp/publickeystore/TestInputOutputStorage.java
+++ b/tests/com/sun/midp/publickeystore/TestInputOutputStorage.java
@@ -33,7 +33,9 @@ public class TestInputOutputStorage implements Testlet {
     public void test(TestHarness th) {
         try {
             FileConnection file = (FileConnection)Connector.open("file:////prova");
-            th.check(!file.exists());
+            if (file.exists()) {
+                file.delete();
+            }
             file.create();
 
             RandomAccessStream ras = new RandomAccessStream();
diff --git a/tests/com/sun/midp/util/isolate/TestInterIsolateMutex.java b/tests/com/sun/midp/util/isolate/TestInterIsolateMutex.java
index 579520fd..5d127c2b 100644
--- a/tests/com/sun/midp/util/isolate/TestInterIsolateMutex.java
+++ b/tests/com/sun/midp/util/isolate/TestInterIsolateMutex.java
@@ -49,6 +49,20 @@ class LockerIsolate2 {
     }
 }
 
+class LockerThread extends Thread {
+    public void run() {
+        SecurityToken t = SecurityTokenProvider.getToken();
+        InterIsolateMutex m = InterIsolateMutex.getInstance(t, "mutex");
+
+        m.lock();
+        try {
+            // Give the test some time to test waiting for the lock
+            Thread.sleep(1000);
+        } catch (Exception e) {}
+        m.unlock();
+    }
+}
+
 public class TestInterIsolateMutex implements Testlet {
     public void test(TestHarness th) {
         SecurityToken t = SecurityTokenProvider.getToken();
@@ -128,5 +142,59 @@ public class TestInterIsolateMutex implements Testlet {
         } catch (Exception e) {
             th.fail("Unexpected exception: " + e);
         }
+
+        m.unlock();
+
+        try {
+            Isolate iso1 = new Isolate("com.sun.midp.util.isolate.LockerIsolate1", new String[] {});
+            Isolate iso2 = new Isolate("com.sun.midp.util.isolate.LockerIsolate2", new String[] {});
+
+            iso2.start();
+            iso1.start();
+
+            m.lock();
+            m.unlock();
+
+            iso2.waitForExit();
+            iso1.waitForExit();
+        } catch (Exception e) {
+            th.fail("Unexpected exception: " + e);
+        }
+
+        try {
+            Isolate iso = new Isolate("com.sun.midp.util.isolate.LockerIsolate2", new String[] {});
+            LockerThread lockerThread = new LockerThread();
+
+            lockerThread.start();
+
+            try {
+                Thread.yield();
+            } catch (Exception e) {}
+
+            iso.start();
+
+            iso.waitForExit();
+            lockerThread.join();
+        } catch (Exception e) {
+            th.fail("Unexpected exception: " + e);
+        }
+
+        try {
+            Isolate iso = new Isolate("com.sun.midp.util.isolate.LockerIsolate2", new String[] {});
+            LockerThread lockerThread = new LockerThread();
+
+            iso.start();
+
+            try {
+                Thread.yield();
+            } catch (Exception e) {}
+
+            lockerThread.start();
+
+            iso.waitForExit();
+            lockerThread.join();
+        } catch (Exception e) {
+            th.fail("Unexpected exception: " + e);
+        }
     }
 }