Index: src/OFSet.h
==================================================================
--- src/OFSet.h
+++ src/OFSet.h
@@ -34,10 +34,13 @@
 typedef BOOL (^of_set_filter_block_t)(id object);
 #endif
 
 /**
  * \brief An abstract class for an unordered set of unique objects.
+ *
+ * \warning Do not mutate objects that are in a set! Changing the hash of
+ *	    objects in a set breaks the internal representation of the set!
  */
 @interface OFSet: OFObject <OFCollection, OFCopying, OFMutableCopying,
     OFSerialization>
 /**
  * \brief Creates a new set.