-AC_CHECK_HEADER(portab.h,,AC_MSG_ERROR([Alex \"portability headers\" (portab.h an friends) not found!]))
-AC_CHECK_HEADER(imp.h,,AC_MSG_ERROR([Alex \"portability headers\" (portab.h an friends) not found!]))
-AC_CHECK_HEADER(exp.h,,AC_MSG_ERROR([Alex \"portability headers\" (portab.h an friends) not found!]))
+AC_CHECK_HEADER(portab.h,[
+ AC_CHECK_HEADER(imp.h,,AC_MSG_ERROR([Alex \"portability headers\" (portab.h an friends) not found!]))
+ AC_CHECK_HEADER(exp.h,,AC_MSG_ERROR([Alex \"portability headers\" (portab.h an friends) not found!]))
+],[
+ AC_CHECK_HEADER(/usr/local/include/portab.h,,AC_MSG_ERROR([Alex \"portability headers\" (portab.h an friends) not found!]))
+ AC_CHECK_HEADER(/usr/local/include/imp.h,,AC_MSG_ERROR([Alex \"portability headers\" (portab.h an friends) not found!]))
+ AC_CHECK_HEADER(/usr/local/include/exp.h,,AC_MSG_ERROR([Alex \"portability headers\" (portab.h an friends) not found!]))
+ CFLAGS="$CFLAGS -I/usr/local/include"
+])