@@ -482,11 +482,11 @@
 + (void)initialize
 {
 	if (self != [OFNumber class])
 		return;
 
-	placeholder.isa = [OFNumberPlaceholder class];
+	object_setClass((id)&placeholder, [OFNumberPlaceholder class]);
 
 #ifdef OF_OBJFW_RUNTIME
 	numberTag =
 	    objc_registerTaggedPointerClass([OFTaggedPointerNumber class]);
 #endif