diff --git a/system/src/Grav/Common/Twig/TwigExtension.php b/system/src/Grav/Common/Twig/TwigExtension.php
index e12fa9a4c..eff3e53fd 100644
--- a/system/src/Grav/Common/Twig/TwigExtension.php
+++ b/system/src/Grav/Common/Twig/TwigExtension.php
@@ -119,6 +119,7 @@ class TwigExtension extends \Twig_Extension
             new \Twig_SimpleFunction('get_cookie', [$this, 'getCookie']),
             new \Twig_SimpleFunction('redirect_me', [$this, 'redirectFunc']),
             new \Twig_SimpleFunction('range', [$this, 'rangeFunc']),
+            new \Twig_SimpleFunction('isajaxrequest', [$this, 'isAjaxFunc']),
         ];
     }
 
@@ -892,4 +893,17 @@ class TwigExtension extends \Twig_Extension
     {
         return range($start, $end, $step);
     }
+
+    /**
+     * Check if HTTP_X_REQUESTED_WITH has been set to xmlhttprequest,
+     * in which case we may unsafely assume ajax. Non critical use only.
+     *
+     * @return true if HTTP_X_REQUESTED_WITH exists and has been set to xmlhttprequest
+     */
+    public function isAjaxFunc()
+    {
+        return (
+            !empty($_SERVER['HTTP_X_REQUESTED_WITH'])
+            && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest');
+    }
 }