diff --git a/calendar/resources/locale/en-US/calendar.dtd b/calendar/resources/locale/en-US/calendar.dtd
index 8f24dae83a22..2126524025f1 100644
--- a/calendar/resources/locale/en-US/calendar.dtd
+++ b/calendar/resources/locale/en-US/calendar.dtd
@@ -207,6 +207,7 @@
 <!ENTITY calendar.dayview.button.label          "Day View" >
 <!ENTITY calendar.weekview.button.label         "Week View" >
 <!ENTITY calendar.monthview.button.label        "Month View" >
+<!ENTITY calendar.onlyworkday.checkbox.label    "Monday-Friday Only" >
 
 <!ENTITY calendar.menu.options.modify       "Edit" >
 <!ENTITY calendar.menu.options.remove       "Delete" >