diff --git a/src/OrdinalNumber.php b/src/OrdinalNumber.php
index 4229c54..d8106eb 100755
--- a/src/OrdinalNumber.php
+++ b/src/OrdinalNumber.php
@@ -103,7 +103,7 @@ public static function convert( $num, $appendAnd = false, $titleCase = false ){
 	 *
 	 * @return {string} 
 	 */
-	private function steppedOrd( $num, $stepSize, $ordinalForm, $wordForm ){
+	private static function steppedOrd( $num, $stepSize, $ordinalForm, $wordForm ){
 		$strNum = (string)$num;
 		$strStep = (string)$stepSize;