@@ -19,12 +19,13 @@
 
 OF_ASSUME_NONNULL_BEGIN
 
 @class OFMutableData;
 
+OF_SUBCLASSING_RESTRICTED
 @interface OFAdjacentArray: OFArray
 {
 	OFMutableData *_array;
 }
 @end
 
 OF_ASSUME_NONNULL_END