--- a/src/ch/ethz/ssh2/Connection.java	Mon Aug 04 11:42:15 2014 -0700
+++ b/src/ch/ethz/ssh2/Connection.java	Mon Aug 04 12:11:12 2014 -0700
@@ -672,13 +672,13 @@
      * run forever.
      */
 
-    public void close() {
+    public synchronized void close() {
         log.debug("Connection.close()");
         Throwable t = new Throwable("Closed due to user request.");
         close(t, false);
     }
 
-    public void close(Throwable t, boolean hard) {
+    public synchronized void close(Throwable t, boolean hard) {
         log.debug(String.format("Connection.close(%s hard=%b)", t.getMessage(), hard));
         if (cm != null) {
             cm.closeAllChannels();