diff --git a/CHANGES.md b/CHANGES.md
index c2628f21..1b8fc1d4 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -5,7 +5,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-Last release of this plugin is 8.6.0 (October, 9th 2023).
+Last release of this plugin is 8.6.1 (October, 10th 2023).
+
+## v8.6.1 - 10 oct. 2023
+- fix: revert to old Viewer
 
 ## v8.6.0 - 9 oct. 2023
 - chore: Update PHP integration to 8.5.0
diff --git a/thirdpartylibs.xml b/thirdpartylibs.xml
index 0af160ba..b06a0bf7 100644
--- a/thirdpartylibs.xml
+++ b/thirdpartylibs.xml
@@ -3,14 +3,14 @@
     <library>
         <location>integration</location>
         <name>MathType Web Integration PHP library</name>
-        <version>8.5.0</version>
+        <version>8.6.0</version>
         <license>GPL</license>
         <licenseversion>3.0+</licenseversion>
     </library>
     <library>
         <location>render</location>
         <name>MathType Web Integration JavaScript SDK</name>
-        <version>8.5.0</version>
+        <version>8.6.0</version>
         <license>GPL</license>
         <licenseversion>3.0+</licenseversion>
     </library>
diff --git a/version.php b/version.php
index 4658bd40..f54521a8 100644
--- a/version.php
+++ b/version.php
@@ -25,8 +25,8 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version = 2023100900;
-$plugin->release = '8.6.0';
+$plugin->version = 2023101000;
+$plugin->release = '8.6.1';
 $plugin->requires = 2011120511;
 $plugin->maturity = MATURITY_STABLE;
 $plugin->component = 'filter_wiris';