constraint expression

Hello,

I am having problems adding a simple expression to a table level
constraint.
Here is an example of one which postgresql 7.4.3 does not accept.

create table test (a int, b int, c int, 
constraint aname check (((a=0) and (b is not null)) or ((a=1) and (c
is not null)));

Should this work?  It is complaining 'ERROR:  syntax error at or near
";" at character 126'

Thanks