@@ -17,12 +17,13 @@
 
 #import "OFCharacterSet.h"
 
 OF_ASSUME_NONNULL_BEGIN
 
+OF_SUBCLASSING_RESTRICTED
 @interface OFRangeCharacterSet: OFCharacterSet
 {
 	of_range_t _range;
 }
 @end
 
 OF_ASSUME_NONNULL_END