diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1ea23464..cbab0fde 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [UNRELEASE]
 
+### Fixed
+
+- Fix validation for mandatory multiple dropdown
+
 ## [1.21.21] - 2025-03-21
 
 ### Fixed
diff --git a/inc/container.class.php b/inc/container.class.php
index 93c9de2c..d8cc983f 100644
--- a/inc/container.class.php
+++ b/inc/container.class.php
@@ -1521,8 +1521,7 @@ public static function validateValues($data, $itemtype, $massiveaction)
             if (
                 $field['mandatory'] == 1
                 && (
-                    $value === null
-                    || $value === ''
+                    empty($value)
                     || (($field['type'] === 'dropdown' || preg_match('/^dropdown-.+/i', $field['type'])) && $value == 0)
                     || (in_array($field['type'], ['date', 'datetime']) && $value == 'NULL')
                 )