add constraint deferrable, syntax error

Why am I getting this?

xdb=# alter table templates add constraint manager_uid_is_invalid check ((constraint_checker('manager',manager,null,null)) = 'OK') DEFERRABLE ;

ERROR:  syntax error at or near "DEFERRABLE"

LINE 1: ...int_checker('manager',manager,null,null)) = 'OK') DEFERRABLE...

v8.3.4 on linux