diff --git a/SoObjects/Mailer/SOGoMailObject.h b/SoObjects/Mailer/SOGoMailObject.h
index 535d11ca2..1965bf3ff 100644
--- a/SoObjects/Mailer/SOGoMailObject.h
+++ b/SoObjects/Mailer/SOGoMailObject.h
@@ -42,6 +42,7 @@
 @class NSData;
 @class NSDictionary;
 @class NSException;
+@class NSMutableArray;
 @class NSString;
 
 @class NGImap4Envelope;