Arrays and foreign keys

Seems that it's not possible to combine arrays and foreign keys ?

CREATE TABLE table1 (
       fld1               integer NOT NULL,
       number          integer,
       level              integer,
 PRIMARY KEY (fld1)
);

CREATE TABLE table2 (
      pkey             integer NOT NULL,
      arvar              integer[],
 PRIMARY KEY (pkey),
 FOREIGN KEY (arvar) REFERENCES table1(fld1)
);


This works, but the following insert complains that 

ERROR:  Unable to identify an operator '=' for types 'int4' and '_int4'
        You will have to retype this query using an explicit cast

-- 
Kaare Rasmussen            --Linux, spil,--        Tlf:        3816 2582
Kaki Data                tshirts, merchandize      Fax:        3816 2582
Howitzvej 75               ben 14.00-18.00        Email: kar@webline.dk
2000 Frederiksberg        Lrdag 11.00-17.00       Web:      www.suse.dk