diff --git a/packages/thunderbird-config.xml b/packages/thunderbird-config.xml
index 00b39ba..f0ca0f6 100644
--- a/packages/thunderbird-config.xml
+++ b/packages/thunderbird-config.xml
@@ -22,6 +22,8 @@
 
         <upgrade include="install" />
 
+        <downgrade include="install" />
+
         <remove cmd='%COMSPEC% /C del /F "%PROG%\defaults\pref\autoconf.js"' />
         <remove cmd='%COMSPEC% /C del /F "%PROG%\thunderbird.cfg"' />
         <remove cmd='%COMSPEC% /C reg delete "%REG_PATH%" /v "ConfigRevision" /f' />