Index: src/OFCountedSet_hashtable.h
==================================================================
--- src/OFCountedSet_hashtable.h
+++ src/OFCountedSet_hashtable.h
@@ -19,8 +19,7 @@
 @class OFMutableDictionary_hashtable;
 
 @interface OFCountedSet_hashtable: OFCountedSet
 {
 	OFMutableDictionary_hashtable *dictionary;
-	unsigned long mutations;
 }
 @end

Index: src/OFCountedSet_hashtable.m
==================================================================
--- src/OFCountedSet_hashtable.m
+++ src/OFCountedSet_hashtable.m
@@ -214,12 +214,10 @@
 
 	[dictionary OF_setObject: count
 			  forKey: object
 			 copyKey: NO];
 
-	mutations++;
-
 	objc_autoreleasePoolPop(pool);
 }
 
 - (void)removeObject: (id)object
 {
@@ -237,14 +235,12 @@
 				  forKey: object
 				 copyKey: NO];
 	else
 		[dictionary removeObjectForKey: object];
 
-	mutations++;
-
 	objc_autoreleasePoolPop(pool);
 }
 
 - (void)makeImmutable
 {
 }
 @end

Index: src/OFMutableSet_hashtable.h
==================================================================
--- src/OFMutableSet_hashtable.h
+++ src/OFMutableSet_hashtable.h
@@ -19,8 +19,7 @@
 @class OFMutableDictionary_hashtable;
 
 @interface OFMutableSet_hashtable: OFMutableSet
 {
 	OFMutableDictionary_hashtable *dictionary;
-	unsigned long mutations;
 }
 @end

Index: src/OFMutableSet_hashtable.m
==================================================================
--- src/OFMutableSet_hashtable.m
+++ src/OFMutableSet_hashtable.m
@@ -33,21 +33,17 @@
 - (void)addObject: (id)object
 {
 	[dictionary OF_setObject: [OFNumber numberWithSize: 1]
 			  forKey: object
 			 copyKey: NO];
-
-	mutations++;
 }
 
 - (void)removeObject: (id)object
 {
 	[dictionary removeObjectForKey: object];
-
-	mutations++;
 }
 
 - (void)makeImmutable
 {
 	object_setClass(self, [OFSet_hashtable class]);
 }
 @end