@@ -85,10 +85,16 @@
 					       length: 4];
 
 		break;
 	}
 
+	/*
+	 * 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;
 }
 
 BOOL
 of_base64_decode(OFDataArray *data, const char *str, size_t len)