diff --git a/README.md b/README.md
index a6614e5..86ed162 100644
--- a/README.md
+++ b/README.md
@@ -105,7 +105,7 @@ FAQ
     bitcoin-node> waiting for SSH...
     Received disconnect from 10.1.1.200 port 22:2: Too many authentication failures
     ```
-    * **A:** Somehow ssh-agent and nixops don't play well together (see also https://github.com/NixOS/nixops/issues/256), if you have a few keys already added to your ssh-agent. Killing and restarting the ssh-agent should fix the problem. Also make sure you don't have something like
+    * **A:** Somehow ssh-agent and nixops don't play well together. Try killing the ssh-agent. Also make sure you don't have something like
     ```
     Host *
         PubkeyAuthentication no
@@ -159,5 +159,3 @@ Open VirtualBox
 File -> Host Network Manager -> Create
 This should create a hostadapter named vboxnet0
 ```
-
-
diff --git a/nix-bitcoin.nix b/nix-bitcoin.nix
index f95c696..63f7205 100644
--- a/nix-bitcoin.nix
+++ b/nix-bitcoin.nix
@@ -1,11 +1,7 @@
 { config, pkgs, ... }:
  let
-   unstable-pkgs-git = builtins.fetchGit {
-     url = "https://github.com/nixos/nixpkgs-channels";
-     ref = "nixpkgs-unstable";
-     rev = "8349329617ffa70164c5a16b049c2ef5f59416bd";
-   };
-   unstable-pkgs = import unstable-pkgs-git { };
+   nixpkgs-pinned = import ./nixpkgs-pinned.nix;
+   nixpkgs-unstable = import nixpkgs-pinned.nixpkgs-unstable { };
 
    # Custom packages
    nodeinfo = (import pkgs/nodeinfo.nix) { inherit pkgs; };
@@ -18,14 +14,14 @@ in {
   disabledModules = [ "services/security/tor.nix" ];
   imports = [
     ./modules/nix-bitcoin.nix
-    (unstable-pkgs-git + "/nixos/modules/services/security/tor.nix")
+    (nixpkgs-pinned.nixpkgs-unstable + "/nixos/modules/services/security/tor.nix")
   ];
 
   nixpkgs.config.packageOverrides = pkgs: {
     # Use bitcoin and clightning from unstable
-    bitcoin = unstable-pkgs.bitcoin.override { };
-    altcoins.bitcoind = unstable-pkgs.altcoins.bitcoind.override { };
-    clightning = unstable-pkgs.clightning.override { };
+    bitcoin = nixpkgs-unstable.bitcoin.override { };
+    altcoins.bitcoind = nixpkgs-unstable.altcoins.bitcoind.override { };
+    clightning = nixpkgs-unstable.clightning.override { };
 
     # Add custom packages
     inherit nodeinfo;
diff --git a/secrets/generate_secrets.sh b/secrets/generate_secrets.sh
index b25d47b..d2cd607 100755
--- a/secrets/generate_secrets.sh
+++ b/secrets/generate_secrets.sh
@@ -7,7 +7,6 @@ if [ -e "$SECRETSFILE" ]; then
     exit 1
 fi
 
-echo Installing apg through nix-env
 echo Write secrets to $SECRETSFILE
 {
     echo \{
diff --git a/shell.nix b/shell.nix
index 5c9efe3..11f4d93 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,10 +1,5 @@
 let
-  # Pin nixpkgs
-  nixpkgs = builtins.fetchGit {
-    url = "https://github.com/nixos/nixpkgs-channels";
-    ref = "nixos-18.09";
-    rev = "001b34abcb4d7f5cade707f7fd74fa27cbabb80b";
-  };
+  nixpkgs = (import ./nixpkgs-pinned.nix).nixpkgs;
 in
 with import nixpkgs { };
 
@@ -15,6 +10,11 @@ stdenv.mkDerivation rec {
 
   shellHook = ''
     export NIX_PATH="nixpkgs=${nixpkgs}:."
+    # ssh-agent and nixops don't play well together (see
+    # https://github.com/NixOS/nixops/issues/256). I'm getting `Received disconnect
+    # from 10.1.1.200 port 22:2: Too many authentication failures` if I have a few
+    # keys already added to my ssh-agent.
+    export SSH_AUTH_SOCK=""
     figlet "nix-bitcoin"
     ./secrets/generate_secrets.sh
   '';