@@ -29,15 +29,18 @@
 @interface OFBlock: OFObject
 + (instancetype)alloc OF_UNAVAILABLE;
 - (instancetype)init OF_UNAVAILABLE;
 @end
 
+OF_SUBCLASSING_RESTRICTED
 @interface OFStackBlock: OFBlock
 @end
 
+OF_SUBCLASSING_RESTRICTED
 @interface OFGlobalBlock: OFBlock
 @end
 
+OF_SUBCLASSING_RESTRICTED
 @interface OFMallocBlock: OFBlock
 @end
 
 OF_ASSUME_NONNULL_END