diff --git a/modules/libpref/src/init/all.js b/modules/libpref/src/init/all.js

index 4e40cfa..b44ec96 100644

--- a/modules/libpref/src/init/all.js

+++ b/modules/libpref/src/init/all.js

@@ -1024,7 +1024,7 @@ pref("intl.charsetmenu.browser.cache.size", 5);

pref("intl.charset.detector", "chrome://global/locale/intl.properties");

pref("intl.charset.default", "chrome://global-platform/locale/intl.properties");

pref("intl.ellipsis", "chrome://global-platform/locale/intl.properties");

-pref("intl.locale.matchOS", false);

+pref("intl.locale.matchOS", true);

// fallback charset list for Unicode conversion (converting from Unicode)

// currently used for mail send only to handle symbol characters (e.g Euro, trademark, smartquotes)

// for ISO-8859-1