diff -Nru update-notifier-0.150/debian/changelog update-notifier-0.151/debian/changelog
--- update-notifier-0.150/debian/changelog	2014-01-08 13:36:58.000000000 -0500
+++ update-notifier-0.151/debian/changelog	2014-01-10 16:39:28.000000000 -0500
@@ -1,3 +1,10 @@
+update-notifier (0.151) trusty; urgency=low
+
+  * If there are no updates available, still nag the user if a reboot is
+    required, in case the notification window was dismissed. (LP: #1033226)
+
+ -- Marc Deslauriers <marc.deslauriers@ubuntu.com>  Fri, 10 Jan 2014 16:37:56 -0500
+
 update-notifier (0.150) trusty; urgency=low
 
   * Update the location of apport/autoreport from /etc to /var/lib.
diff -Nru update-notifier-0.150/src/update.c update-notifier-0.151/src/update.c
--- update-notifier-0.150/src/update.c	2013-07-12 13:07:51.000000000 -0400
+++ update-notifier-0.151/src/update.c	2014-01-10 17:13:53.000000000 -0500
@@ -551,6 +551,7 @@
    priv->num_upgrades = 0;
    priv->num_security = 0;
    int exit_status = 0;
+   int reboot = 0;
    GError *error = NULL;
 
    char *cmd[] = { "/usr/bin/nice",
@@ -558,6 +559,7 @@
 		   UPGRADE_CHECKER, 
 		   NULL };
    char *ret;
+   struct stat buf;
 
    if(g_spawn_sync(NULL, cmd, NULL,  
 		   G_SPAWN_STDOUT_TO_DEV_NULL, 
@@ -615,10 +617,10 @@
    
    g_debug_update("%s returned %i (security: %i)", UPGRADE_CHECKER, priv->num_upgrades, priv->num_security);
 
-   if (priv->num_upgrades == 0) {
+   reboot = (stat("/var/run/reboot-required", &buf) == 0);
 
+   if ((priv->num_upgrades == 0) && !reboot) {
       // check if the periodic file is very old
-      struct stat buf;
       if ((stat("/var/lib/apt/periodic/update-success-stamp", &buf) == 0) &&
 	  (time(NULL) - buf.st_mtime > OUTDATED_NAG_AGE) ) 
 	 g_timeout_add_seconds(OUTDATED_NAG_WAIT, (GSourceFunc)outdated_nag, ta);
@@ -641,7 +643,7 @@
    update_trayicon_update_tooltip(ta, priv->num_upgrades);
 
    tray_applet_ui_set_visible(ta, FALSE);
-   if (auto_launch_now(ta))
+   if (auto_launch_now(ta) || reboot)
    {
       g_spawn_command_line_async("nice ionice -c3 update-manager "
 			         "--no-update --no-focus-on-map", NULL);