@@ -22,10 +22,13 @@
 #import "OFNotImplementedException.h"
 
 static struct {
 	Class isa;
 } placeholder;
+
+@interface OFMutableDictionary_placeholder: OFDictionary
+@end
 
 @implementation OFMutableDictionary_placeholder
 - init
 {
 	return (id)[[OFMutableDictionary_hashtable alloc] init];