--- old/src/java.desktop/unix/classes/sun/awt/X11/XMSelection.java	2018-10-06 18:31:57.502820458 +0900
+++ new/src/java.desktop/unix/classes/sun/awt/X11/XMSelection.java	2018-10-06 18:31:57.122808336 +0900
@@ -200,7 +200,7 @@
             if (log.isLoggable(PlatformLogger.Level.FINE)) {
                 log.fine("client messags = " + xce);
             }
-            long timestamp = xce.get_data(0);
+            long timestamp = xce.get_data(0) & 0xFFFFFFFFL;
             long atom = xce.get_data(1);
             long owner = xce.get_data(2);
             long data = xce.get_data(3);