diff --git a/include/init/requirements.php b/include/init/requirements.php
index 5df8d4867..93542bb3d 100755
--- a/include/init/requirements.php
+++ b/include/init/requirements.php
@@ -146,7 +146,7 @@ foreach ($settings as $name => $values) {
     } elseif ($values['type'] == 'ext') {
         $status = extension_loaded($name);
     } elseif ($values['type'] == 'function') {
-        $status = is_callable($name);
+        $status = ((function_exists($name) && is_callable($name)) ? 1: 0);
     } else {
         $ini = str_replace(['k', 'M'], ['000', '000000'], ini_get($name));
         $real = str_replace(['k', 'M'], ['000', '000000'], $description);