'errno' undefined?

I get the following when building cvs:

gcc -I../../include  -O2 -g -Wall -Wmissing-prototypes
-Wmissing-declarations   -c pqformat.c -o pqformat.o
pqformat.c: In function `pq_endmessage':
pqformat.c:219: `errno' undeclared (first use in this function)
pqformat.c:219: (Each undeclared identifier is reported only once
pqformat.c:219: for each function it appears in.)
make: *** [pqformat.o] Error 1

Any ideas?

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