postgres 6.5 with RH 6.0

Hello

 I compile postgres 6.4.2 and 6.5 in RedHat 6.0, but I get this message
error with pgaccess and when try to compile a C program:

[postgres@escarpia vipscgi]$ gcc -o altapersonal altapersonal.c -lpq
/usr/lib/libpq.so: undefined reference to `crypt'
collect2: ld returned 1 exit status


I have install 6.4.2 in RedHat 5.2 and things go well, but in RH6.0 I
can't.

Somebody can help me?

Atentamente
Cesar Lombao Vazquez
EXT 233-INFRAESTRUCTURAS
DYCSA