diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 6b153b92e..99a177006 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -13,7 +13,7 @@ jobs:
     - uses: actions/checkout@v2
     - uses: cachix/install-nix-action@v11
       with:
-        nix_path: nixpkgs=channel:nixos-unstable
+        nix_path: nixpkgs=channel:nixos-20.09
     - uses: cachix/cachix-action@v6
       with:
         name: nix-community
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 22eec3228..0c3e6cae0 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,8 +1,7 @@
 image: nixos/nix:latest
 
 variables:
-  # Pinned 2020-09-11.
-  NIX_PATH: "nixpkgs=https://github.com/NixOS/nixpkgs/archive/6d4b93323e7f78121f8d6db6c59f3889aa1dd931.tar.gz"
+  NIX_PATH: "nixpkgs=channel:nixos-20.09"
 
 stages:
   - test