diff --git a/lib/modinfolib.php b/lib/modinfolib.php
index 576f4604368..17a499c8206 100644
--- a/lib/modinfolib.php
+++ b/lib/modinfolib.php
@@ -2426,7 +2426,7 @@ class section_info implements IteratorAggregate {
     public function __empty($name) {
         if (method_exists($this, 'get_'.$name) ||
                 property_exists($this, '_'.$name) ||
-                in_array($name, self::$sectionformatoptions[$this->modinfo->get_course()->format])) {
+                array_key_exists($name, self::$sectionformatoptions[$this->modinfo->get_course()->format])) {
             $value = $this->__get($name);
             return empty($value);
         }
@@ -2451,7 +2451,7 @@ class section_info implements IteratorAggregate {
             return $this->cachedformatoptions[$name];
         }
         // precheck if the option is defined in format to avoid unnecessary DB queries in get_format_options()
-        if (in_array($name, self::$sectionformatoptions[$this->modinfo->get_course()->format])) {
+        if (array_key_exists($name, self::$sectionformatoptions[$this->modinfo->get_course()->format])) {
             $formatoptions = course_get_format($this->modinfo->get_course())->get_format_options($this);
             return $formatoptions[$name];
         }