diff --git a/SoObjects/SOGo/SOGoFolder.m b/SoObjects/SOGo/SOGoFolder.m
index 219d7d1ce..ac9d019c8 100644
--- a/SoObjects/SOGo/SOGoFolder.m
+++ b/SoObjects/SOGo/SOGoFolder.m
@@ -107,7 +107,7 @@
 
 - (void) setDisplayName: (NSString *) newDisplayName
 {
-  ASSIGN (displayName, [newDisplayName mutableCopy]);
+  ASSIGN (displayName, (NSMutableString *)newDisplayName);
 }
 
 - (NSString *) displayName