--- a/jdk/src/share/classes/sun/tools/jconsole/JConsole.java	Thu Aug 22 15:54:50 2013 -0700
+++ b/jdk/src/share/classes/sun/tools/jconsole/JConsole.java	Wed Aug 21 17:15:44 2013 +0200
@@ -858,6 +858,10 @@
                 try {
                     updateInterval = Integer.parseInt(arg.substring(10)) *
                         1000;
+                    if (updateInterval <= 0) {
+                        usage();
+                        return;
+                    }
                 } catch (NumberFormatException ex) {
                     usage();
                     return;