1 files changed, 1 insertions, 1 deletions
diff --git a/MLKCons.h b/MLKCons.h
index 3d17ff5..f2fee99 100644
--- a/MLKCons.h
+++ b/MLKCons.h
@@ -21,7 +21,7 @@
 @class NSArray;
 
 
-@interface MLKCons : MLKLispValue
+@interface MLKCons : MLKLispValue <NSCopying>
 {
   id _car;
   id _cdr;