diff --git a/nixos/modules/services/networking/nat.nix b/nixos/modules/services/networking/nat.nix
index bfaf30c11783..df4246d216d8 100644
--- a/nixos/modules/services/networking/nat.nix
+++ b/nixos/modules/services/networking/nat.nix
@@ -19,6 +19,8 @@ let
     iptables -w -t nat -D POSTROUTING -j nixos-nat-post 2>/dev/null || true
     iptables -w -t nat -F nixos-nat-post 2>/dev/null || true
     iptables -w -t nat -X nixos-nat-post 2>/dev/null || true
+
+    ${cfg.extraStopCommands}
   '';
 
   setupNat = ''
@@ -59,6 +61,8 @@ let
 	--to-destination ${cfg.dmzHost}
     ''}
 
+    ${cfg.extraCommands}
+
     # Append our chains to the nat tables
     iptables -w -t nat -A PREROUTING -j nixos-nat-pre
     iptables -w -t nat -A POSTROUTING -j nixos-nat-post
@@ -170,6 +174,28 @@ in
         '';
     };
 
+    networking.nat.extraCommands = mkOption {
+      type = types.lines;
+      default = "";
+      example = "iptables -A INPUT -p icmp -j ACCEPT";
+      description =
+        ''
+          Additional shell commands executed as part of the nat
+          initialisation script.
+        '';
+    };
+
+    networking.nat.extraStopCommands = mkOption {
+      type = types.lines;
+      default = "";
+      example = "iptables -D INPUT -p icmp -j ACCEPT || true";
+      description =
+        ''
+          Additional shell commands executed as part of the nat
+          teardown script.
+        '';
+    };
+
   };
 
 
diff --git a/pkgs/applications/misc/toot/default.nix b/pkgs/applications/misc/toot/default.nix
index d1b1daa26d6f..be8652619125 100644
--- a/pkgs/applications/misc/toot/default.nix
+++ b/pkgs/applications/misc/toot/default.nix
@@ -1,19 +1,19 @@
-{ stdenv, fetchFromGitHub, pythonPackages }:
+{ stdenv, fetchFromGitHub, python3Packages }:
 
-pythonPackages.buildPythonApplication rec {
-  version = "0.15.0";
+python3Packages.buildPythonApplication rec {
+  version = "0.16.2";
   name    = "toot-${version}";
 
   src = fetchFromGitHub {
     owner  = "ihabunek";
     repo   = "toot";
     rev    = "${version}";
-    sha256 = "08k913gw0ip2q686z9k63bcn1n5s4w6b7jj6jmmamm427xmibkph";
+    sha256 = "19n6rmm44y24zvkpk56vd2xmx49sn6wc5qayi1jm83jlnlbbwfh7";
   };
 
-  checkInputs = with pythonPackages; [ pytest ];
+  checkInputs = with python3Packages; [ pytest ];
 
-  propagatedBuildInputs = with pythonPackages;
+  propagatedBuildInputs = with python3Packages;
     [ requests beautifulsoup4 future ];
 
   checkPhase = ''
diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index fc4074dd8cd9..cba1f9a54a24 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -72,7 +72,7 @@ in rec {
       sphinx = pkgs.python27Packages.sphinx;
     };
     ghc822 = callPackage ../development/compilers/ghc/8.2.2.nix rec {
-      bootPkgs = packages.ghc7103Binary;
+      bootPkgs = packages.ghc821Binary;
       inherit (bootPkgs) hscolour alex happy;
       inherit buildPlatform targetPlatform;
       sphinx = pkgs.python3Packages.sphinx;