diff --git a/tcpdf/include/tcpdf_fonts.php b/tcpdf/include/tcpdf_fonts.php
index 6cca641..23d89bc 100644
--- a/tcpdf/include/tcpdf_fonts.php
+++ b/tcpdf/include/tcpdf_fonts.php
@@ -1996,7 +1996,7 @@ public static function getUniord($uch) {
 	 * @author Nicola Asuni
 	 * @public static
 	 */
-	public static function UTF8StringToArray($str, $isunicode=true, &$currentfont) {
+	public static function UTF8StringToArray($str, $isunicode, &$currentfont) {
 		if ($isunicode) {
 			// requires PCRE unicode support turned on
 			$chars = TCPDF_STATIC::pregSplit('//','u', $str, -1, PREG_SPLIT_NO_EMPTY);
@@ -2018,7 +2018,7 @@ public static function UTF8StringToArray($str, $isunicode=true, &$currentfont) {
 	 * @since 3.2.000 (2008-06-23)
 	 * @public static
 	 */
-	public static function UTF8ToLatin1($str, $isunicode=true, &$currentfont) {
+	public static function UTF8ToLatin1($str, $isunicode, &$currentfont) {
 		$unicode = self::UTF8StringToArray($str, $isunicode, $currentfont); // array containing UTF-8 unicode values
 		return self::UTF8ArrToLatin1($unicode);
 	}
@@ -2034,7 +2034,7 @@ public static function UTF8ToLatin1($str, $isunicode=true, &$currentfont) {
 	 * @since 1.53.0.TC005 (2005-01-05)
 	 * @public static
 	 */
-	public static function UTF8ToUTF16BE($str, $setbom=false, $isunicode=true, &$currentfont) {
+	public static function UTF8ToUTF16BE($str, $setbom, $isunicode, &$currentfont) {
 		if (!$isunicode) {
 			return $str; // string is not in unicode
 		}
@@ -2054,7 +2054,7 @@ public static function UTF8ToUTF16BE($str, $setbom=false, $isunicode=true, &$cur
 	 * @since 2.1.000 (2008-01-08)
 	 * @public static
 	 */
-	public static function utf8StrRev($str, $setbom=false, $forcertl=false, $isunicode=true, &$currentfont) {
+	public static function utf8StrRev($str, $setbom, $forcertl, $isunicode, &$currentfont) {
 		return self::utf8StrArrRev(self::UTF8StringToArray($str, $isunicode, $currentfont), $str, $setbom, $forcertl, $isunicode, $currentfont);
 	}
 
@@ -2071,7 +2071,7 @@ public static function utf8StrRev($str, $setbom=false, $forcertl=false, $isunico
 	 * @since 4.9.000 (2010-03-27)
 	 * @public static
 	 */
-	public static function utf8StrArrRev($arr, $str='', $setbom=false, $forcertl=false, $isunicode=true, &$currentfont) {
+	public static function utf8StrArrRev($arr, $str, $setbom, $forcertl, $isunicode, &$currentfont) {
 		return self::arrUTF8ToUTF16BE(self::utf8Bidi($arr, $str, $forcertl, $isunicode, $currentfont), $setbom);
 	}
 
@@ -2087,7 +2087,7 @@ public static function utf8StrArrRev($arr, $str='', $setbom=false, $forcertl=fal
 	 * @since 2.4.000 (2008-03-06)
 	 * @public static
 	 */
-	public static function utf8Bidi($ta, $str='', $forcertl=false, $isunicode=true, &$currentfont) {
+	public static function utf8Bidi($ta, $str, $forcertl, $isunicode, &$currentfont) {
 		// paragraph embedding level
 		$pel = 0;
 		// max level