diff --git a/src/main/java/info/istlab/IoTP/MqttWindow.java b/src/main/java/info/istlab/IoTP/MqttWindow.java
index 15398f6..994272c 100644
--- a/src/main/java/info/istlab/IoTP/MqttWindow.java
+++ b/src/main/java/info/istlab/IoTP/MqttWindow.java
@@ -116,7 +116,7 @@
         setSize(600, 500);
         setLocation(centerOfScreen(getSize()));
         setVisible(true);
-        setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
+        setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
         jtf.addActionListener(this);
         addWindowListener(this); // Xをおしたらserial closeする
 
@@ -128,7 +128,7 @@
     public void run() {
         subscriber = new MqttSubscriber(brokerjtf.getText(), brokerportjtf.getText(), topicjtf.getText(), this);
         jta.setBackground(Color.YELLOW);
-        appendToJTA("Try Connecting to broker: tcp://" + brokerjtf.getText() + ":" + brokerportjtf.getText() + ".\n");
+        appendToJTA("Try Connecting to broker : tcp://" + brokerjtf.getText() + ":" + brokerportjtf.getText() + "\n");
         try {
             subscriber.subscribe();
         } catch (MqttException | InterruptedException e1) {