@@ -219,10 +219,17 @@
 #if __has_attribute(__objc_root_class__)
 # define OF_ROOT_CLASS __attribute__((__objc_root_class__))
 #else
 # define OF_ROOT_CLASS
 #endif
+
+#if __has_attribute(__objc_subclassing_restricted__)
+# define OF_SUBCLASSING_RESTRICTED \
+	__attribute__((__objc_subclassing_restricted__))
+#else
+# define OF_SUBCLASSING_RESTRICTED
+#endif
 
 #ifdef __GNUC__
 # if defined(__x86_64__) || defined(__amd64__)
 #  define OF_X86_64_ASM
 # elif defined(__i386__)