diff --git a/src/MDUnitsSet.php b/src/MDUnitsSet.php
index 4b2ab62..a467097 100644
--- a/src/MDUnitsSet.php
+++ b/src/MDUnitsSet.php
@@ -21,7 +21,7 @@ class MDUnitsSet extends MDValueSet {
      *
      * @return array<string>
      */
-    function getLengthUnitsTLed(MDTlLoader $tlLoader):array {
+    public static function getLengthUnitsTLed(MDTlLoader $tlLoader):array {
         return parent::getTlUnsortedList($tlLoader, self::UNITS_LENGTH, "units_length_set", "units_length_set");
 
     }
@@ -33,7 +33,7 @@ class MDUnitsSet extends MDValueSet {
      *
      * @return array<string>
      */
-    function getWeightUnitsTLed(MDTlLoader $tlLoader):array {
+    public static function getWeightUnitsTLed(MDTlLoader $tlLoader):array {
         return parent::getTlUnsortedList($tlLoader, self::UNITS_WEIGHT, "units_weight_set", "units_weight_set");
 
     }