diff --git a/configure.ac b/configure.ac
index 701e14d91692e6e69cbda4cae1b6a871938eea36..cd95f7da34502c9da1d8de829bc0c12f4019c9b9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -55,8 +55,7 @@ AM_PROG_AR
 
 AM_PROG_LEX
 # Hack to get lex include dir, ticket #575
-AC_PATH_PROG([LEXPATH], [$LEX])
-AC_SUBST([LEXINC], [$(eval "echo $LEXPATH | sed 's|\(.*\)$LEX$|\1../include|'")])
+AC_SUBST([LEXINC], [$(echo "$(dirname "$(which $LEX)")"/../include)])
 
 AC_CHECK_PROG([YACC], [bison], [bison])
 if test -z "$YACC"; then