@@ -17,10 +17,11 @@
 
 #import "OFURLHandler.h"
 
 OF_ASSUME_NONNULL_BEGIN
 
+OF_SUBCLASSING_RESTRICTED
 @interface OFFileURLHandler: OFURLHandler
 + (bool)of_directoryExistsAtPath: (OFString *)path;
 @end
 
 OF_ASSUME_NONNULL_END