diff --git a/Headers/Foundation/NSCalendar.h b/Headers/Foundation/NSCalendar.h
index 7fbe84412..da8eb05cb 100644
--- a/Headers/Foundation/NSCalendar.h
+++ b/Headers/Foundation/NSCalendar.h
@@ -32,6 +32,7 @@
 #include <Foundation/NSObject.h>
 
 @class NSDate;
+@class NSCalendar;
 @class NSLocale;
 @class NSString;
 @class NSTimeZone;