diff --git a/configure.ac b/configure.ac
index 4830e22..2da490a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2,7 +2,12 @@
 # Process this file with autoconf to produce a configure script.
 
 AC_PREREQ([2.63])
-AC_INIT(iptables-ext-dns,1.0.3 , mimuret@gmail.com)
+m4_define([VERSION_MAJOR],[1])
+m4_define([VERSION_MINOR],[1])
+m4_define([VERSION_MICRO],[0])
+AC_INIT(iptables-ext-dns,m4_defn([VERSION_MAJOR]).m4_defn([VERSION_MINOR]).m4_defn([VERSION_MICRO]), mimuret@gmail.com, iptables-ext-dns)
+AC_SUBST(VERSION_INFO, [VERSION_MAJOR:VERSION_MINOR:VERSION_MICRO])
+
 AC_CONFIG_AUX_DIR(misc)
 AM_INIT_AUTOMAKE([foreign])
 AC_CONFIG_SRCDIR([extensions/libxt_dns.c])
diff --git a/extensions/Makefile.am b/extensions/Makefile.am
index 5a99d24..885d449 100644
--- a/extensions/Makefile.am
+++ b/extensions/Makefile.am
@@ -1,4 +1,4 @@
 nobase_lib_LTLIBRARIES = xtables/libxt_dns.la
 xtables_libxt_dns_la_SOURCES = libxt_dns.c
 xtables_libxt_dns_la_CFLAGS  = -lresolv -I../include
-xtables_libxt_dns_la_LDFLAGS = -version-info 1:3:0
+xtables_libxt_dns_la_LDFLAGS = -version-info @VERSION_INFO@
diff --git a/iptables-ext-dns.spec b/iptables-ext-dns.spec.in
similarity index 98%
rename from iptables-ext-dns.spec
rename to iptables-ext-dns.spec.in
index 8abc2d9..bf63342 100644
--- a/iptables-ext-dns.spec
+++ b/iptables-ext-dns.spec.in
@@ -3,7 +3,7 @@
 
 Summary: Administration tool for IPv4/IPv6 TCP/UDP packet filtering.
 Name: iptables-ext-dns
-Version: 1.0.3
+Version: @PACKAGE_VERSION@
 Release: 0%{?dist}
 License: GPLv3
 Group: System Environment/Base
diff --git a/modules/xt_dns.c b/modules/xt_dns.c
index f3fec23..86ca5e4 100644
--- a/modules/xt_dns.c
+++ b/modules/xt_dns.c
@@ -184,8 +184,7 @@ static bool dns_mt_tcp(const struct sk_buff *skb, XT_PARAM *par,
         HOTDROP(par);
         return false;
     }
-    if (!(th->ack & th->psh) ||
-        (ntohs(th->source) != DNS_PORT && ntohs(th->dest) != DNS_PORT)) {
+    if (!(th->ack & th->psh) || (th->dest != htons(DNS_PORT))) {
         DEBUG_PRINT("not dns packet");
         return false;
     }
@@ -206,7 +205,7 @@ static bool dns_mt_udp(const struct sk_buff *skb, XT_PARAM *par,
         HOTDROP(par);
         return false;
     }
-    if (ntohs(uh->source) != DNS_PORT && ntohs(uh->dest) != DNS_PORT) {
+    if (uh->dest != htons(DNS_PORT)) {
         DEBUG_PRINT("not dns packet");
         return false;
     }