diff --git a/flake.lock b/flake.lock
index b06a406..68efe45 100644
--- a/flake.lock
+++ b/flake.lock
@@ -17,16 +17,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1637709854,
-        "narHash": "sha256-y98gkOBUEiPAmwRhZPzTQ0YayZKPS2loNgA0GcNewMM=",
+        "lastModified": 1639488789,
+        "narHash": "sha256-Ey12CBni1jlEGoW4eH4X0hugWs25MxHMcNH4N8VVX0U=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "9c43581935a23d56734bd02da0ba8e7fda21e747",
+        "rev": "ce635e9dca8f7e2bfab19a3667d7e697c019c68b",
         "type": "github"
       },
       "original": {
         "owner": "nixos",
-        "ref": "release-21.05",
+        "ref": "release-21.11",
         "repo": "nixpkgs",
         "type": "github"
       }
diff --git a/flake.nix b/flake.nix
index b28c6c1..8d4b5da 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,30 +1,65 @@
 {
   description = "Lsyncd (Live Syncing Daemon)";
   
-  inputs.nixpkgs.url = "github:nixos/nixpkgs/release-21.05";
+  inputs.nixpkgs.url = "github:nixos/nixpkgs/release-21.11";
   inputs.flake-utils.url = "github:numtide/flake-utils";
 
   outputs = { self, nixpkgs, flake-utils }:
     flake-utils.lib.eachDefaultSystem
       (system:
         let
-          pkgs = nixpkgs.legacyPackages.${system};
+          pkgs = (import nixpkgs {
+            inherit system;
+            # Makes the config pure as well. See <nixpkgs>/top-level/impure.nix:
+            config = {
+              allowBroken = true;
+            };}); #.legacyPackages.${system};
           defaultDeps = with pkgs; [
             gcc
             cmake
+            gnumake
             glib
             rsync
             openssh
+            curl
           ];
           version = builtins.elemAt
             (builtins.match ''.*set\(.LSYNCD_VERSION ([0-9\.]*).*''
               (builtins.substring 0 500
                 (builtins.readFile ./CMakeLists.txt))) 0;
+          mylua5_4 = pkgs.lua5_4.override({
+            packageOverrides =  luaself: luaprev: {
+              luarocks = luaprev.luarocks-3_7;
+            };
+          });
+          luaposix35 = mylua: mylua.pkgs.buildLuarocksPackage {
+            pname = "luaposix";
+            lua = mylua;
+            version = "35.1-1";
+            knownRockspec = (pkgs.fetchurl {
+              url    = "https://luarocks.org/luaposix-35.1-1.rockspec";
+              sha256 = "1n6c7qyabj2y95jmbhf8fxbrp9i73kphmwalsam07f9w9h995xh1";
+            }).outPath;
+            src = pkgs.fetchurl {
+              url    = "http://github.com/luaposix/luaposix/archive/v35.1.zip";
+              sha256 = "1c03chkzwr2p1wd0hs1bafl2890fqbrfc3qk0wxbd202gc6128zi";
+            };
+
+            #
+            propagatedBuildInputs = [ mylua ];
+
+            meta = {
+              homepage = "http://github.com/luaposix/luaposix/";
+              description = "Lua bindings for POSIX";
+              license.fullName = "MIT/X11";
+            };
+          };
+
           buildTypes = { 
-            lua5_1 = [pkgs.lua5_1 pkgs.lua51Packages.luaposix pkgs.lua51Packages.penlight];
-            lua5_2 = [pkgs.lua5_2 pkgs.lua52Packages.luaposix pkgs.lua52Packages.penlight];
-            lua5_3 = [pkgs.lua5_3 pkgs.lua53Packages.luaposix pkgs.lua53Packages.penlight];
-            lua5_4 = [pkgs.lua5_4 pkgs.lua54Packages.luaposix pkgs.lua54Packages.penlight];
+            lua5_1 = [pkgs.lua5_1 pkgs.lua51Packages.luaposix];
+            lua5_2 = [pkgs.lua5_2 pkgs.lua52Packages.luaposix];
+            lua5_3 = [pkgs.lua5_3 pkgs.lua53Packages.luaposix];
+            lua5_4 = [pkgs.lua5_3 (luaposix35 mylua5_4)];
           };
         in
         let
@@ -33,10 +68,12 @@
             name = "lsyncd";
 
             src = ./.;
-            
-            # nativeBuildInputs = [ pkgs.qt5.wrapQtAppsHook ]; 
+
             buildInputs = defaultDeps ++ luaPackages;
-        });
+          });
+          mkDev = packages: pkgs.mkShell {
+            propagatedBuildInputs = defaultDeps ++ packages;
+          };
         in
         {
           packages = {
@@ -47,10 +84,15 @@
               lsyncd_lua5_4 = mkLsync buildTypes.lua5_4;
           };
 
+          devShells = {
+              lsyncd = mkDev buildTypes.lua5_3;
+              lsyncd_lua5_1 = mkDev buildTypes.lua5_1;
+              lsyncd_lua5_2 = mkDev buildTypes.lua5_2;
+              lsyncd_lua5_3 = mkDev buildTypes.lua5_3;
+              lsyncd_lua5_4 = mkDev buildTypes.lua5_4;
+          };
+
           defaultPackage = self.packages.${system}.lsyncd;
-          # devShell = pkgs.mkShell {
-          #   buildInputs = defaultDeps ++ buildTypes.lua5_3;
-          # };
         }
       );
 }
\ No newline at end of file
diff --git a/tests/testlib.lua b/tests/testlib.lua
index 34fee4e..5a5ba69 100644
--- a/tests/testlib.lua
+++ b/tests/testlib.lua
@@ -1,8 +1,7 @@
 -- common testing environment
 posix = require( 'posix' )
 string = require( 'string' )
-path = require( 'pl.path' )
-stringx = require( 'pl.stringx' )
+
 local sys_stat = require "posix.sys.stat"
 
 -- escape codes to colorize output on terminal
@@ -94,10 +93,39 @@ function writefile
 	return true
 end
 
+function splitpath(P)
+    local i = #P
+    local ch = P:sub(i,i)
+    while i > 0 and ch ~= "/" do
+        i = i - 1
+        ch = P:sub(i,i)
+    end
+    if i == 0 then
+        return '',P
+    else
+        return P:sub(1,i-1), P:sub(i+1)
+    end
+end
+
+function isabs(p)
+	return string.sub(p, 1, 2) == "/"
+end
+
+function abspath(P,pwd)
+	P = P:gsub('[\\/]$','')
+	if not isabs(P) then
+		local rv = posix.unistd.getcwd() .. "/" .. P
+		return rv
+	end
+	return P
+end
+
+
 function script_path()
 	-- local str = debug.getinfo(2, "S").source:sub(2)
 	-- return str:match("(.*/)")
-	return path.dirname(path.abspath(debug.getinfo(1).short_src))
+	local dir, file = splitpath(abspath(debug.getinfo(1).short_src))
+	return dir
 end
 
 function which(exec)
@@ -159,6 +187,11 @@ function startSshd()
 	return true
 end
 
+
+function strip(s)
+	return s:match "^%s*(.-)%s*$"
+end
+
 --
 -- Stop test ssh server
 --
@@ -169,7 +202,7 @@ function stopSshd()
 	then
 		return false
 	end
-	pid = stringx.strip(f:read("*a"))
+	pid = strip(f:read("*a"))
 	posix.kill(tonumber(pid))
 end