@@ -82,11 +82,11 @@
  * If @ref nextOption returned `?` or `:`, this returns the option which was
  * unknown or for which the argument was missing.@n
  * If this returns `-`, the last option is only available as a long option (see
  * lastLongOption).
  */
-@property (readonly) of_unichar_t lastOption;
+@property (readonly, nonatomic) of_unichar_t lastOption;
 
 /*!
  * The long option for the last parsed option, or `nil` if the last parsed
  * option was not passed as a long option by the user.
  *