diff --git a/CHANGELOG.TXT b/CHANGELOG.TXT
index 9320f2e8..70b4f541 100644
--- a/CHANGELOG.TXT
+++ b/CHANGELOG.TXT
@@ -1,3 +1,6 @@
+6.6.4 (2023-09-06)
+	- Fix GitHub automation tests.
+
 6.6.3 (2023-09-06)
 	- Fix SPDX license ID (#591)
 	- Fix warning "array offset on value of type null" (#620)
diff --git a/VERSION b/VERSION
index e411592c..b22e754a 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-6.6.3
+6.6.4
diff --git a/composer.json b/composer.json
index 0d693bad..654cb415 100644
--- a/composer.json
+++ b/composer.json
@@ -12,7 +12,7 @@
         "barcodes"
     ],
     "homepage": "http://www.tcpdf.org/",
-    "version": "6.6.3",
+    "version": "6.6.4",
     "license": "LGPL-3.0-or-later",
     "authors": [
         {
diff --git a/include/tcpdf_fonts.php b/include/tcpdf_fonts.php
index a71c84b7..6f7f8280 100644
--- a/include/tcpdf_fonts.php
+++ b/include/tcpdf_fonts.php
@@ -1708,7 +1708,10 @@ public static function unichrASCII($c) {
 
 	/**
 	 * Converts array of UTF-8 characters to UTF16-BE string.<br>
-	 * Based on: http://www.faqs.org/rfcs/rfc2781.html
+	 * Based permissions:
+  contents: read
+
+on: http://www.faqs.org/rfcs/rfc2781.html
 	 * <pre>
 	 *   Encoding UTF-16:
 	 *
@@ -1898,7 +1901,10 @@ public static function uniord($uch) {
 	/**
 	 * Converts UTF-8 character to integer value.<br>
 	 * Invalid byte sequences will be replaced with 0xFFFD (replacement character)<br>
-	 * Based on: http://www.faqs.org/rfcs/rfc3629.html
+	 * Based permissions:
+  contents: read
+
+on: http://www.faqs.org/rfcs/rfc3629.html
 	 * <pre>
 	 *    Char. number range  |        UTF-8 octet sequence
 	 *       (hexadecimal)    |              (binary)
@@ -1909,7 +1915,13 @@ public static function uniord($uch) {
 	 *    0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
 	 *    ---------------------------------------------------------------------
 	 *
-	 *   ABFN notation:
+	 *   ABFN notatipermissions:
+  contents: read
+
+permissions:
+  contents: read
+
+on:
 	 *   ---------------------------------------------------------------------
 	 *   UTF8-octets = *( UTF8-char )
 	 *   UTF8-char   = UTF8-1 / UTF8-2 / UTF8-3 / UTF8-4
diff --git a/include/tcpdf_static.php b/include/tcpdf_static.php
index 07d1c359..ecaf8205 100644
--- a/include/tcpdf_static.php
+++ b/include/tcpdf_static.php
@@ -55,7 +55,7 @@ class TCPDF_STATIC {
 	 * Current TCPDF version.
 	 * @private static
 	 */
-	private static $tcpdf_version = '6.6.3';
+	private static $tcpdf_version = '6.6.4';
 
 	/**
 	 * String alias for total number of pages.
diff --git a/tcpdf.php b/tcpdf.php
index f5958e32..bed07887 100644
--- a/tcpdf.php
+++ b/tcpdf.php
@@ -1,7 +1,7 @@
 <?php
 //============================================================+
 // File name   : tcpdf.php
-// Version     : 6.6.3
+// Version     : 6.6.4
 // Begin       : 2002-08-03
 // Last Update : 2023-09-06
 // Author      : Nicola Asuni - Tecnick.com LTD - www.tecnick.com - info@tecnick.com
@@ -104,7 +104,7 @@
  * Tools to encode your unicode fonts are on fonts/utils directory.</p>
  * @package com.tecnick.tcpdf
  * @author Nicola Asuni
- * @version 6.6.3
+ * @version 6.6.4
  */
 
 // TCPDF configuration
@@ -128,7 +128,7 @@
  * TCPDF project (http://www.tcpdf.org) has been originally derived in 2002 from the Public Domain FPDF class by Olivier Plathey (http://www.fpdf.org), but now is almost entirely rewritten.<br>
  * @package com.tecnick.tcpdf
  * @brief PHP class for generating PDF documents without requiring external extensions.
- * @version 6.6.3
+ * @version 6.6.4
  * @author Nicola Asuni - info@tecnick.com
  * @IgnoreAnnotation("protected")
  * @IgnoreAnnotation("public")