diff --git a/default.nix b/default.nix
index c0d3d7f5a4ec51f39fa0d64486e3051f5788d6dc..f1c5e37ea433eb5add61f81b6c9ed3c4b359ce25 100644
--- a/default.nix
+++ b/default.nix
@@ -1,2 +1,2 @@
-{ pkgs ? import <nixpkgs> { overlays = [ (import ./overlays.nix) ]; } }:
+{ pkgs ? import ./nixpkgs.nix { } }:
 pkgs.python27Packages.callPackage ./zkapauthorizer.nix { }
diff --git a/nixpkgs.nix b/nixpkgs.nix
new file mode 100644
index 0000000000000000000000000000000000000000..c3086292210b535df82387f5c149b4c905e4d5a8
--- /dev/null
+++ b/nixpkgs.nix
@@ -0,0 +1,11 @@
+{ pkgs ? import <nixpkgs> { } }:
+let
+  nixpkgs = fetchTarball
+  { url = "https://github.com/NixOS/nixpkgs-channels/archive/4557b9f1f50aa813ae673fe6fcd30ca872968947.tar.gz";
+    sha256 = "0cam48cn042axcik9vqxsqjc2hwyb2grjbjxacsn4w0y1zk6k6l2";
+  };
+  args =
+  { overlays = [ (import ./overlays.nix) ];
+  };
+in
+pkgs.callPackage nixpkgs args
diff --git a/overlays.nix b/overlays.nix
index 7e503de7cb5f4c38b5b9d2b13a25987089b74eeb..395e00027d7100f1178402e0f4c2553a18b02e0c 100644
--- a/overlays.nix
+++ b/overlays.nix
@@ -1,4 +1,6 @@
 self: super: {
+  openssl = self.openssl_1_1;
+
   python27 = super.python27.override {
     packageOverrides = python-self: python-super: {
       # new tahoe-lafs dependency
diff --git a/shell.nix b/shell.nix
index 9831badbecba81acb54a50f95fe677e6ca9a57e6..82afac579e08b5fe57cd8fb8e787fbdd19e78605 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,4 +1,4 @@
-{ pkgs ? import <nixpkgs> { overlays = [ (import ./overlays.nix) ]; } }:
+{ pkgs ? import ./nixpkgs.nix { } }:
 let
   zkapauthorizer = pkgs.callPackage ./default.nix { };
 in