Index: src/OFMutableDictionary.h
==================================================================
--- src/OFMutableDictionary.h
+++ src/OFMutableDictionary.h
@@ -12,11 +12,15 @@
 #import "OFDictionary.h"
 
 /**
  * The OFMutableDictionary class is a class for using mutable hash tables.
  */
-@interface OFMutableDictionary: OFDictionary {}
+@interface OFMutableDictionary: OFDictionary
+{
+	unsigned long mutations;
+}
+
 /**
  * Sets a key to an object. A key can be any object.
  *
  * \param key The key to set
  * \param obj The object to set the key to

Index: src/OFMutableDictionary.m
==================================================================
--- src/OFMutableDictionary.m
+++ src/OFMutableDictionary.m
@@ -87,10 +87,12 @@
 		    ![data[i].key isEqual: key]; i++);
 
 	/* Key not in dictionary */
 	if (i >= size || ![data[i].key isEqual: key]) {
 		resize(self, isa, count + 1, &data, &size);
+
+		mutations++;
 
 		i = hash & (size - 1);
 		for (; i < size && data[i].key != nil; i++);
 
 		/* In case the last bucket is already used */
@@ -150,10 +152,11 @@
 	[data[i].key release];
 	[data[i].object release];
 	data[i].key = nil;
 
 	count--;
+	mutations++;
 	resize(self, isa, count, &data, &size);
 
 	return self;
 }