diff --git a/.gitignore b/.gitignore
index 94000a9..0834a00 100644
--- a/.gitignore
+++ b/.gitignore
@@ -26,7 +26,7 @@ depcomp
 install-sh
 libtool
 ltmain.sh
-m4/
+m4/l*.m4
 missing
 ylwrap
 Makefile
diff --git a/configure.ac b/configure.ac
index a8b8be7..db9552f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -29,74 +29,14 @@ AC_PROG_CC
 AC_PROG_CC_STDC
 AM_PROG_CC_C_O
 AC_PROG_LIBTOOL
+LT_INIT
 AC_PROG_YACC
 
-CFLAGS="$CFLAGS -Wall -std=gnu99 -fno-strict-aliasing"
-
-case $host_os in
-	*darwin*)
-		HOST_OS=darwin
-		AC_DEFINE(SETEUID_BREAKS_SETUID,[],[setuid after seteuid does not work])
-		AC_DEFINE(BROKEN_SETREUID,[], [Broken setreuid])
-		AC_DEFINE(BROKEN_SETREGID,[], [Broken setregid])
-		AC_DEFINE(YYSTYPE_IS_DECLARED,[], [Broken bison])
-		AC_DEFINE([SPT_TYPE], [SPT_REUSEARGV])
-		;;
-	*freebsd*)
-		HOST_OS=freebsd
-		AC_SUBST([PROG_LDADD], ['-lthr'])
-		;;
-	*linux*)
-		HOST_OS=linux
-		CFLAGS="$CFLAGS -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_GNU_SOURCE"
-		AC_DEFINE([SPT_TYPE], [SPT_REUSEARGV])
-		;;
-	*netbsd*)
-		HOST_OS=netbsd
-		;;
-	*openbsd*)
-		HOST_OS=openbsd
-		AC_DEFINE([HAVE_ATTRIBUTE__BOUNDED__], [1], [OpenBSD has __bounded__])
-		AC_DEFINE([HAVE_ATTRIBUTE__DEAD], [1], [OpenBSD has __dead])
-		;;
-	*solaris*)
-		HOST_OS=solaris
-		CFLAGS="$CFLAGS -D__EXTENSIONS__ -D_XOPEN_SOURCE=600 -DBSD_COMP"
-		AC_SUBST([PLATFORM_LDADD], ['-lnsl -lsocket'])
-		;;
-	*) ;;
-esac
-
-AM_CONDITIONAL([HOST_DARWIN],  [test x$HOST_OS = xdarwin])
-AM_CONDITIONAL([HOST_FREEBSD], [test x$HOST_OS = xfreebsd])
-AM_CONDITIONAL([HOST_LINUX],   [test x$HOST_OS = xlinux])
-AM_CONDITIONAL([HOST_NETBSD],  [test x$HOST_OS = xnetbsd])
-AM_CONDITIONAL([HOST_OPENBSD],  [test x$HOST_OS = xopenbsd])
-AM_CONDITIONAL([HOST_SOLARIS], [test x$HOST_OS = xsolaris])
+CHECK_OS_OPTIONS
 
 AC_CHECK_FUNC([dl_iterate_phdr],,
 	[AC_SEARCH_LIBS([dl_iterate_phdr],[dl])])
 
-save_cflags="$CFLAGS"
-CFLAGS=-Wno-pointer-sign
-AC_MSG_CHECKING([whether CC supports -Wno-pointer-sign])
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([])],
-	[AC_MSG_RESULT([yes])]
-	[AM_CFLAGS=-Wno-pointer-sign],
-	[AC_MSG_RESULT([no])]
-)
-CFLAGS="$save_cflags $AM_CFLAGS"
-
-AC_MSG_CHECKING([if compiling with clang])
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [[
-#ifndef __clang__
-	not clang
-#endif
-	]])],
-	[AC_MSG_RESULT([yes])]
-	[CLANG_FLAGS=-Qunused-arguments],
-	[AC_MSG_RESULT([no])]
-)
 CFLAGS="$CFLAGS $CLANG_CFLAGS"
 LDFLAGS="$LDFLAGS $CLANG_FLAGS"
 
diff --git a/m4/check-os-options.m4 b/m4/check-os-options.m4
new file mode 100644
index 0000000..2b5b563
--- /dev/null
+++ b/m4/check-os-options.m4
@@ -0,0 +1,45 @@
+AC_DEFUN([CHECK_OS_OPTIONS], [
+
+CFLAGS="$CFLAGS -Wall -std=gnu99 -fno-strict-aliasing"
+
+case $host_os in
+	*darwin*)
+		HOST_OS=darwin
+		AC_DEFINE(SETEUID_BREAKS_SETUID,[],[setuid after seteuid does not work])
+		AC_DEFINE(BROKEN_SETREUID,[], [Broken setreuid])
+		AC_DEFINE(BROKEN_SETREGID,[], [Broken setregid])
+		AC_DEFINE(YYSTYPE_IS_DECLARED,[], [Broken bison])
+		AC_DEFINE([SPT_TYPE], [SPT_REUSEARGV])
+		;;
+	*freebsd*)
+		HOST_OS=freebsd
+		AC_SUBST([PROG_LDADD], ['-lthr'])
+		;;
+	*linux*)
+		HOST_OS=linux
+		CFLAGS="$CFLAGS -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_GNU_SOURCE"
+		AC_DEFINE([SPT_TYPE], [SPT_REUSEARGV])
+		;;
+	*netbsd*)
+		HOST_OS=netbsd
+		;;
+	*openbsd*)
+		HOST_OS=openbsd
+		AC_DEFINE([HAVE_ATTRIBUTE__BOUNDED__], [1], [OpenBSD has __bounded__])
+		AC_DEFINE([HAVE_ATTRIBUTE__DEAD], [1], [OpenBSD has __dead])
+		;;
+	*solaris*)
+		HOST_OS=solaris
+		CFLAGS="$CFLAGS -D__EXTENSIONS__ -D_XOPEN_SOURCE=600 -DBSD_COMP"
+		AC_SUBST([PLATFORM_LDADD], ['-lnsl -lsocket'])
+		;;
+	*) ;;
+esac
+
+AM_CONDITIONAL([HOST_DARWIN],  [test x$HOST_OS = xdarwin])
+AM_CONDITIONAL([HOST_FREEBSD], [test x$HOST_OS = xfreebsd])
+AM_CONDITIONAL([HOST_LINUX],   [test x$HOST_OS = xlinux])
+AM_CONDITIONAL([HOST_NETBSD],  [test x$HOST_OS = xnetbsd])
+AM_CONDITIONAL([HOST_OPENBSD],  [test x$HOST_OS = xopenbsd])
+AM_CONDITIONAL([HOST_SOLARIS], [test x$HOST_OS = xsolaris])
+])