--- configure.ac.old	2006-10-03 13:40:20.000000000 +0200
+++ configure.ac.old	2006-10-03 13:43:03.000000000 +0200
@@ -296,6 +296,7 @@ 
 AC_MSG_RESULT($rtc_ok)
 
 if test "$PRECISION" = "l"; then
+	AC_CHECK_LIB(ml, sinl)
 	AC_CHECK_FUNCS([cosl sinl tanl], [], [AC_MSG_ERROR([long-double precision requires long-double trigonometric routines])])
 fi