diff --git a/cnf/configure_func.sh b/cnf/configure_func.sh
index 45e1134..c587456 100644
--- a/cnf/configure_func.sh
+++ b/cnf/configure_func.sh
@@ -44,7 +44,8 @@ checkfunc d_chsize 'chsize' "0,0"
 checkfunc d_class 'class'
 checkfunc d_clearenv 'clearenv' "" 'stdlib.h'
 checkfunc d_closedir 'closedir' "NULL" 'dirent.h sys/types.h'
-checkfunc d_crypt 'crypt' "NULL,NULL" 'crypt.h'
+test "$i_crypt"  = 'define' && checkfunc d_crypt 'crypt' "NULL,NULL" 'crypt.h unistd.h'
+test "$i_crypt" != 'define' && checkfunc d_crypt 'crypt' "NULL,NULL" 'unistd.h'
 checkfunc d_ctermid 'ctermid'
 checkfunc d_ctime64 'ctime64'
 checkfunc d_cuserid 'cuserid'