diff --git a/pom.xml b/pom.xml
index bacc4d6..0112cc0 100644
--- a/pom.xml
+++ b/pom.xml
@@ -100,6 +100,7 @@
         <artifactId>maven-surefire-plugin</artifactId>
         <version>2.14.1</version>
         <configuration>
+          <argLine>-Dfile.encoding=UTF-8</argLine>
           <systemProperties>
             <property>
               <name>java.util.logging.config.file</name>
diff --git a/src/main/java/com/github/nkzawa/socketio/client/Socket.java b/src/main/java/com/github/nkzawa/socketio/client/Socket.java
index 313f724..579938b 100644
--- a/src/main/java/com/github/nkzawa/socketio/client/Socket.java
+++ b/src/main/java/com/github/nkzawa/socketio/client/Socket.java
@@ -146,6 +146,7 @@ public class Socket extends Emitter {
                 List<Object> _args = new ArrayList<Object>(args.length + 1);
                 _args.add(event);
                 _args.addAll(Arrays.asList(args));
+
                 JSONArray jsonArgs = new JSONArray();
                 for (Object arg : _args) {
                     jsonArgs.put(arg);
@@ -157,6 +158,7 @@ public class Socket extends Emitter {
                 if (_args.get(_args.size() - 1) instanceof Ack) {
                     logger.fine(String.format("emitting packet with ack id %d", Socket.this.ids));
                     Socket.this.acks.put(Socket.this.ids, (Ack)_args.remove(_args.size() - 1));
+                    jsonArgs.remove(jsonArgs.length() - 1);
                     packet.id = Socket.this.ids++;
                 }
 
@@ -240,6 +242,10 @@ public class Socket extends Emitter {
                 this.onack(packet);
                 break;
 
+            case Parser.BINARY_ACK:
+                this.onack(packet);
+                break;
+
             case Parser.DISCONNECT:
                 this.ondisconnect();
                 break;
@@ -276,7 +282,9 @@ public class Socket extends Emitter {
                 if (sent[0]) return;
                 sent[0] = true;
                 logger.fine(String.format("sending ack %s", args));
-                Packet<JSONArray> packet = new Packet<JSONArray>(Parser.ACK, new JSONArray(args));
+
+                int type = HasBinaryData.hasBinary(args) ? Parser.BINARY_ACK : Parser.ACK;
+                Packet<JSONArray> packet = new Packet<JSONArray>(type, new JSONArray(args));
                 packet.id = id;
                 self.packet(packet);
             }
diff --git a/src/test/java/com/github/nkzawa/hasbinarydata/HasBinaryDataTest.java b/src/test/java/com/github/nkzawa/hasbinarydata/HasBinaryDataTest.java
new file mode 100644
index 0000000..88ab744
--- /dev/null
+++ b/src/test/java/com/github/nkzawa/hasbinarydata/HasBinaryDataTest.java
@@ -0,0 +1,26 @@
+package com.github.nkzawa.hasbinarydata;
+
+import org.json.JSONArray;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+import java.nio.charset.Charset;
+
+import static org.junit.Assert.assertTrue;
+
+@RunWith(JUnit4.class)
+public class HasBinaryDataTest {
+
+    @Test
+    public void arrayContainsByteArray() {
+        JSONArray arr = new JSONArray("[1, null, 2]");
+        arr.put(1, "asdfasdf".getBytes(Charset.forName("UTF-8")));
+        assertTrue(HasBinaryData.hasBinary(arr));
+    }
+
+    @Test
+    public void byteArray() {
+        assertTrue(HasBinaryData.hasBinary(new byte[0]));
+    }
+}
diff --git a/src/test/java/com/github/nkzawa/socketio/client/ConnectionTest.java b/src/test/java/com/github/nkzawa/socketio/client/ConnectionTest.java
index c0d3167..fb6f022 100644
--- a/src/test/java/com/github/nkzawa/socketio/client/ConnectionTest.java
+++ b/src/test/java/com/github/nkzawa/socketio/client/ConnectionTest.java
@@ -9,6 +9,7 @@ import org.junit.runners.JUnit4;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.nio.charset.Charset;
+import java.util.Date;
 import java.util.Timer;
 import java.util.TimerTask;
 import java.util.concurrent.CountDownLatch;
@@ -76,6 +77,27 @@ public class ConnectionTest extends Connection {
         latch.await();
     }
 
+    @Test(timeout = TIMEOUT)
+    public void receiveDateWithAck() throws URISyntaxException, InterruptedException {
+        final CountDownLatch latch = new CountDownLatch(1);
+        socket = client();
+        socket.on(Socket.EVENT_CONNECT, new Emitter.Listener() {
+            @Override
+            public void call(Object... objects) {
+                socket.emit("getAckDate", new JSONObject("{test: true}"), new Ack() {
+                    @Override
+                    public void call(Object... args) {
+                        assertThat(args[0], instanceOf(String.class));
+                        socket.close();
+                        latch.countDown();
+                    }
+                });
+            }
+        });
+        socket.connect();
+        latch.await();
+    }
+
     @Test(timeout = TIMEOUT)
     public void workWithFalse() throws URISyntaxException, InterruptedException {
         final CountDownLatch latch = new CountDownLatch(1);
@@ -98,6 +120,42 @@ public class ConnectionTest extends Connection {
         latch.await();
     }
 
+    @Test(timeout = TIMEOUT)
+    public void receiveUTF8MultibyteCharacters() throws URISyntaxException, InterruptedException {
+        final CountDownLatch latch = new CountDownLatch(1);
+        final String[] correct = new String[] {
+            "てすと",
+            "Я Б Г Д Ж Й",
+            "Ä ä Ü ü ß",
+            "utf8 — string",
+            "utf8 — string"
+        };
+
+        socket = client();
+        final int[] i = new int[] {0};
+        socket.on(Socket.EVENT_CONNECT, new Emitter.Listener() {
+            @Override
+            public void call(Object... objects) {
+                socket.on("echoBack", new Emitter.Listener() {
+                    @Override
+                    public void call(Object... args) {
+                        assertThat((String)args[0], is(correct[i[0]]));
+                        i[0]++;
+                        if (i[0] == correct.length) {
+                            socket.close();
+                            latch.countDown();
+                        }
+                    }
+                });
+                for (String data : correct) {
+                    socket.emit("echo", data);
+                }
+            }
+        });
+        socket.connect();
+        latch.await();
+    }
+
     @Test(timeout = TIMEOUT)
     public void connectToNamespaceAfterConnectionEstablished() throws URISyntaxException, InterruptedException {
         final CountDownLatch latch = new CountDownLatch(1);
@@ -209,7 +267,7 @@ public class ConnectionTest extends Connection {
     }
 
     @Test(timeout = TIMEOUT)
-    public void notTryToReconnectWithIncorrectPort() throws URISyntaxException, InterruptedException {
+    public void notTryToReconnectWithIncorrectPortWhenReconnectionDisabled() throws URISyntaxException, InterruptedException {
         final CountDownLatch latch = new CountDownLatch(1);
         IO.Options opts = new IO.Options();
         opts.reconnection = false;
@@ -241,6 +299,53 @@ public class ConnectionTest extends Connection {
         latch.await();
     }
 
+    @Test(timeout = TIMEOUT)
+    public void emitDateAsString() throws URISyntaxException, InterruptedException {
+        final CountDownLatch latch = new CountDownLatch(1);
+        socket = client();
+        socket.on(Socket.EVENT_CONNECT, new Emitter.Listener() {
+            @Override
+            public void call(Object... objects) {
+                socket.emit("echo", new Date());
+                socket.on("echoBack", new Emitter.Listener() {
+                    @Override
+                    public void call(Object... args) {
+                        assertThat(args[0], instanceOf(String.class));
+                        socket.close();
+                        latch.countDown();
+                    }
+                });
+            }
+        });
+        socket.connect();
+        latch.await();
+    }
+
+    @Test(timeout = TIMEOUT)
+    public void emitDateInObject() throws URISyntaxException, InterruptedException {
+        final CountDownLatch latch = new CountDownLatch(1);
+        socket = client();
+        socket.on(Socket.EVENT_CONNECT, new Emitter.Listener() {
+            @Override
+            public void call(Object... objects) {
+                JSONObject data = new JSONObject();
+                data.put("date", new Date());
+                socket.emit("echo", data);
+                socket.on("echoBack", new Emitter.Listener() {
+                    @Override
+                    public void call(Object... args) {
+                        assertThat(args[0], instanceOf(JSONObject.class));
+                        assertThat(((JSONObject)args[0]).get("date"), instanceOf(String.class));
+                        socket.close();
+                        latch.countDown();
+                    }
+                });
+            }
+        });
+        socket.connect();
+        latch.await();
+    }
+
     @Test(timeout = TIMEOUT)
     public void sendAndGetBinaryData() throws URISyntaxException, InterruptedException {
         final CountDownLatch latch = new CountDownLatch(1);
diff --git a/src/test/resources/index.js b/src/test/resources/index.js
index c7d2f92..a4e21ba 100644
--- a/src/test/resources/index.js
+++ b/src/test/resources/index.js
@@ -29,6 +29,10 @@ io.of(nsp).on('connection', function(socket) {
     });
   });
 
+  socket.on('getAckDate', function(data, callback) {
+    callback(new Date());
+  });
+
   socket.on('disconnect', function() {
     console.log('disconnect');
   });