diff --git a/includes/html/pages/devices.inc.php b/includes/html/pages/devices.inc.php
index e44d53af5ec9..5a69891f91c0 100644
--- a/includes/html/pages/devices.inc.php
+++ b/includes/html/pages/devices.inc.php
@@ -55,7 +55,7 @@
     if ($vars['format'] == 'graph_' . $option) {
         $listoptions .= '<span class="pagemenu-selected">';
     }
-    $listoptions .= '<a href="' . generate_url($vars, array('format' => 'graph_' . $option, 'from' => '-24h', 'to' => 'now')) . '">' . $text . '</a>';
+    $listoptions .= '<a href="' . generate_url($vars, array('format' => 'graph_' . $option, 'from' => '-24hour', 'to' => 'now')) . '">' . $text . '</a>';
     if ($vars['format'] == 'graph_' . $option) {
         $listoptions .= '</span>';
     }
diff --git a/includes/html/pages/graphs.inc.php b/includes/html/pages/graphs.inc.php
index eccbcddd465d..8ff59e0ed337 100644
--- a/includes/html/pages/graphs.inc.php
+++ b/includes/html/pages/graphs.inc.php
@@ -15,10 +15,10 @@
 }
 
 if (!is_numeric($vars['from'])) {
-    $vars['from'] = $config['time']['day'];
+    $vars['from'] = strtotime($vars['from']) ?: Config::get('time.day');
 }
 if (!is_numeric($vars['to'])) {
-    $vars['to']   = $config['time']['now'];
+    $vars['to'] = strtotime($vars['to']) ?: Config::get('time.now');
 }
 
 preg_match('/^(?P<type>[A-Za-z0-9]+)_(?P<subtype>.+)/', $vars['type'], $graphtype);