diff --git a/calendar/base/content/calendar-views.js b/calendar/base/content/calendar-views.js
index 65e3204ce6d..cb7cb3a0368 100644
--- a/calendar/base/content/calendar-views.js
+++ b/calendar/base/content/calendar-views.js
@@ -278,6 +278,8 @@ function getStyleSheet(aStyleSheetPath) {
             return sheet;
         }
     }
+    // Avoid the js strict "function does not always return a value" warning.
+    return null;
 }
 
 // Updates the style rules for a particular object.  If the object is a