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,PRIMARYKEY (fld1)
 
);

CREATE TABLE table2 (     pkey             integer NOT NULL,     arvar              integer[],PRIMARY KEY
(pkey),FOREIGNKEY (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
anexplicit cast
 

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