diff --git a/nixos/modules/services/networking/softether.nix b/nixos/modules/services/networking/softether.nix
index 9087b75c29c1..65df93a00da9 100644
--- a/nixos/modules/services/networking/softether.nix
+++ b/nixos/modules/services/networking/softether.nix
@@ -5,6 +5,8 @@ with lib;
 let
   cfg = config.services.softether;
 
+  package = cfg.package.override { dataDir = cfg.dataDir; };
+
 in
 {
 
@@ -49,7 +51,7 @@ in
 
       dataDir = mkOption {
         type = types.string;
-        default = "${cfg.package.dataDir}";
+        default = "/var/lib/softether";
         description = ''
           Data directory for SoftEther VPN.
         '';
@@ -64,11 +66,8 @@ in
   config = mkIf cfg.enable (
 
     mkMerge [{
-      environment.systemPackages = [
-          (pkgs.lib.overrideDerivation cfg.package (attrs: {
-            dataDir = cfg.dataDir;
-          }))
-        ];
+      environment.systemPackages = [ package ];
+
       systemd.services."softether-init" = {
         description = "SoftEther VPN services initial task";
         wantedBy = [ "network.target" ];
@@ -80,11 +79,11 @@ in
             for d in vpnserver vpnbridge vpnclient vpncmd; do
                 if ! test -e ${cfg.dataDir}/$d; then
                     ${pkgs.coreutils}/bin/mkdir -m0700 -p ${cfg.dataDir}/$d
-                    install -m0600 ${cfg.package}${cfg.dataDir}/$d/hamcore.se2 ${cfg.dataDir}/$d/hamcore.se2
+                    install -m0600 ${package}${cfg.dataDir}/$d/hamcore.se2 ${cfg.dataDir}/$d/hamcore.se2
                 fi
             done
             rm -rf ${cfg.dataDir}/vpncmd/vpncmd
-            ln -s ${cfg.package}${cfg.dataDir}/vpncmd/vpncmd ${cfg.dataDir}/vpncmd/vpncmd
+            ln -s ${package}${cfg.dataDir}/vpncmd/vpncmd ${cfg.dataDir}/vpncmd/vpncmd
         '';
       };
     }
@@ -97,12 +96,12 @@ in
         wantedBy = [ "network.target" ];
         serviceConfig = {
           Type = "forking";
-          ExecStart = "${cfg.package}/bin/vpnserver start";
-          ExecStop = "${cfg.package}/bin/vpnserver stop";
+          ExecStart = "${package}/bin/vpnserver start";
+          ExecStop = "${package}/bin/vpnserver stop";
         };
         preStart = ''
             rm -rf ${cfg.dataDir}/vpnserver/vpnserver
-            ln -s ${cfg.package}${cfg.dataDir}/vpnserver/vpnserver ${cfg.dataDir}/vpnserver/vpnserver
+            ln -s ${package}${cfg.dataDir}/vpnserver/vpnserver ${cfg.dataDir}/vpnserver/vpnserver
         '';
         postStop = ''
             rm -rf ${cfg.dataDir}/vpnserver/vpnserver
@@ -118,12 +117,12 @@ in
         wantedBy = [ "network.target" ];
         serviceConfig = {
           Type = "forking";
-          ExecStart = "${cfg.package}/bin/vpnbridge start";
-          ExecStop = "${cfg.package}/bin/vpnbridge stop";
+          ExecStart = "${package}/bin/vpnbridge start";
+          ExecStop = "${package}/bin/vpnbridge stop";
         };
         preStart = ''
             rm -rf ${cfg.dataDir}/vpnbridge/vpnbridge
-            ln -s ${cfg.package}${cfg.dataDir}/vpnbridge/vpnbridge ${cfg.dataDir}/vpnbridge/vpnbridge
+            ln -s ${package}${cfg.dataDir}/vpnbridge/vpnbridge ${cfg.dataDir}/vpnbridge/vpnbridge
         '';
         postStop = ''
             rm -rf ${cfg.dataDir}/vpnbridge/vpnbridge
@@ -139,12 +138,12 @@ in
         wantedBy = [ "network.target" ];
         serviceConfig = {
           Type = "forking";
-          ExecStart = "${cfg.package}/bin/vpnclient start";
-          ExecStop = "${cfg.package}/bin/vpnclient stop";
+          ExecStart = "${package}/bin/vpnclient start";
+          ExecStop = "${package}/bin/vpnclient stop";
         };
         preStart = ''
             rm -rf ${cfg.dataDir}/vpnclient/vpnclient
-            ln -s ${cfg.package}${cfg.dataDir}/vpnclient/vpnclient ${cfg.dataDir}/vpnclient/vpnclient
+            ln -s ${package}${cfg.dataDir}/vpnclient/vpnclient ${cfg.dataDir}/vpnclient/vpnclient
         '';
         postStart = ''
             sleep 1
diff --git a/pkgs/servers/softether/4.18.nix b/pkgs/servers/softether/4.18.nix
index 69c6cbe2c864..d8c3fe944cc3 100644
--- a/pkgs/servers/softether/4.18.nix
+++ b/pkgs/servers/softether/4.18.nix
@@ -1,5 +1,6 @@
 { stdenv, fetchurl
-, openssl, readline, ncurses, zlib }:
+, openssl, readline, ncurses, zlib
+, dataDir ? "/var/lib/softether" }:
 
 let
   os = if stdenv.isLinux then "1"
@@ -17,7 +18,6 @@ stdenv.mkDerivation rec {
   version = "4.18";
   build = "9570";
   compiledDate = "2015.07.26";
-  dataDir = "/var/lib/softether";
 
   src = fetchurl {
     url = "http://www.softether-download.com/files/softether/v${version}-${build}-rtm-${compiledDate}-tree/Source_Code/softether-src-v${version}-${build}-rtm.tar.gz";
diff --git a/pkgs/servers/softether/4.20.nix b/pkgs/servers/softether/4.20.nix
index c6ef5a3a4df2..5d6f642ddc0a 100644
--- a/pkgs/servers/softether/4.20.nix
+++ b/pkgs/servers/softether/4.20.nix
@@ -1,5 +1,6 @@
 { stdenv, fetchurl
-, openssl, readline, ncurses, zlib }:
+, openssl, readline, ncurses, zlib
+, dataDir ? "/var/lib/softether" }:
 
 let
   os = if stdenv.isLinux then "1"
@@ -17,7 +18,6 @@ stdenv.mkDerivation rec {
   version = "4.20";
   build = "9608";
   compiledDate = "2016.04.17";
-  dataDir = "/var/lib/softether";
 
   src = fetchurl {
     url = "http://www.softether-download.com/files/softether/v${version}-${build}-rtm-${compiledDate}-tree/Source_Code/softether-src-v${version}-${build}-rtm.tar.gz";
diff --git a/pkgs/servers/softether/4.25.nix b/pkgs/servers/softether/4.25.nix
index b1e9c5c1a455..2dcb69d28f14 100644
--- a/pkgs/servers/softether/4.25.nix
+++ b/pkgs/servers/softether/4.25.nix
@@ -1,5 +1,6 @@
 { stdenv, fetchurl
-, openssl, readline, ncurses, zlib }:
+, openssl, readline, ncurses, zlib
+, dataDir ? "/var/lib/softether" }:
 
 let
   os = if stdenv.isLinux then "1"
@@ -17,7 +18,6 @@ stdenv.mkDerivation rec {
   version = "4.25";
   build = "9656";
   compiledDate = "2018.01.15";
-  dataDir = "/var/lib/softether";
 
   src = fetchurl {
     url = "http://www.softether-download.com/files/softether/v${version}-${build}-rtm-${compiledDate}-tree/Source_Code/softether-src-v${version}-${build}-rtm.tar.gz";