diff --git a/mailnews/mailnews.js b/mailnews/mailnews.js
index 4b55e93fc3e2..8941d49b6400 100644
--- a/mailnews/mailnews.js
+++ b/mailnews/mailnews.js
@@ -230,6 +230,7 @@ pref("mailnews.sort_by_date_received",      false);
 
 pref("mailnews.send_default_charset",       "ISO-8859-1");
 pref("mailnews.view_default_charset",       "ISO-8859-1");
+pref("mailnews.force_charset_override",     false);
 
 pref("mailnews.language_sensitive_font",    true);
 
diff --git a/modules/libpref/src/init/mailnews.js b/modules/libpref/src/init/mailnews.js
index 4b55e93fc3e2..8941d49b6400 100644
--- a/modules/libpref/src/init/mailnews.js
+++ b/modules/libpref/src/init/mailnews.js
@@ -230,6 +230,7 @@ pref("mailnews.sort_by_date_received",      false);
 
 pref("mailnews.send_default_charset",       "ISO-8859-1");
 pref("mailnews.view_default_charset",       "ISO-8859-1");
+pref("mailnews.force_charset_override",     false);
 
 pref("mailnews.language_sensitive_font",    true);