diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index b5ecc8d1adeb..067bfc0fb295 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -23,7 +23,6 @@ jobs:
         CMAKE_OPTIONS: -DLLVM=ON
       macOS:
         imageName: macos-latest
-        NIX_SHELL_OPTIONS: --arg llvmPackages '(import ./nix/nixpkgs.nix).llvmPackages_8'
   pool:
     vmImage: $(imageName)
   steps:
diff --git a/nix/nixpkgs.nix b/nix/nixpkgs.nix
index 5c4dab4175c3..3aafd8b3b618 100644
--- a/nix/nixpkgs.nix
+++ b/nix/nixpkgs.nix
@@ -1,7 +1,7 @@
 import (builtins.fetchTarball {
-    name = "nixos-unstable-2019-10-02";
-    # Commit hash from `git ls-remote https://github.com/nixos/nixpkgs-channels nixos-unstable`
-    url = https://github.com/nixos/nixpkgs/archive/cbf29876cfc2f81186d2e1e233bf992dfcb07fad.tar.gz;
-    # Hash obtained using `nix-prefetch-url --unpack <url>`
-    sha256 = "1fvb6dkmcfhrwki0v8wqfr3c8mmhhzqdjnzbcdyw201dx8dj4iqn";
-  }) {}
+  name = "nixpkgs-unstable-2019-10-07";
+  # Commit hash from `git ls-remote https://github.com/nixos/nixpkgs-channels nixos-unstable`
+  url = https://github.com/nixos/nixpkgs/archive/795b1555a88627f0739188081527f23259fcc1d2.tar.gz;
+  # Hash obtained using `nix-prefetch-url --unpack <url>`
+  sha256 = "0lx1snxgankwv18h3jrzz99fmhk036a2gng4xp92c04nx8mcjlgc";
+}) {}
diff --git a/shell.nix b/shell.nix
index 590beb687d54..891920e5fd8d 100644
--- a/shell.nix
+++ b/shell.nix
@@ -2,7 +2,7 @@
 
 let
   lean = import ./default.nix args;
-  temci = import (builtins.fetchGit { url = http://github.com/parttimenerd/temci.git; rev = "ba1505a7c2de471a5821a2643b34de2d1c1af03e"; }) {};
+  temci = import (builtins.fetchGit { url = http://github.com/parttimenerd/temci.git; rev = "ba1505a7c2de471a5821a2643b34de2d1c1af03e"; }) { inherit pkgs; };
 in pkgs.mkShell.override { stdenv = lean.stdenv; } rec {
   inputsFrom = [ lean ];
   buildInputs = with pkgs; [ temci ccache ninja ];