@@ -349,18 +349,14 @@
 	}
 	[ret replaceOccurrencesOfString: @"\n"
 			     withString: @"\n\t"];
 	[ret appendString: @"\n]"];
 
+	[ret makeImmutable];
+
 	[pool release];
 
-	/*
-	 * Class swizzle the string to be immutable. We declared the return type
-	 * to be OFString*, so it can't be modified anyway. But not swizzling it
-	 * would create a real copy each time -[copy] is called.
-	 */
-	ret->isa = [OFString class];
 	return ret;
 }
 
 - (OFXMLElement*)XMLElementBySerializing
 {