diff --git a/calendar/locales/en-US/lightning-l10n.js b/calendar/locales/en-US/lightning-l10n.js
index 868504b8f3..f1ecce4b0b 100644
--- a/calendar/locales/en-US/lightning-l10n.js
+++ b/calendar/locales/en-US/lightning-l10n.js
@@ -17,7 +17,5 @@ pref("calendar.week.d4thursdaysoff", false);
 pref("calendar.week.d5fridaysoff", false);
 pref("calendar.week.d6saturdaysoff", true);
 
-pref("general.useragent.locale", "@AB_CD@");
-
 # categories
 pref("calendar.categories.names", "Anniversary,Birthday,Business,Calls,Clients,Competition,Customer,Favorites,Follow up,Gifts,Holidays,Ideas,Issues,Meeting,Miscellaneous,Personal,Projects,Public Holiday,Status,Suppliers,Travel,Vacation");
diff --git a/im/locales/en-US/all-l10n.js b/im/locales/en-US/all-l10n.js
index 6e0520e894..8d0fb84064 100755
--- a/im/locales/en-US/all-l10n.js
+++ b/im/locales/en-US/all-l10n.js
@@ -4,5 +4,4 @@
 
 #filter substitution
 
-pref("general.useragent.locale", "@AB_CD@");
 pref("spellchecker.dictionary", "@AB_CD@");