diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 2c5c5a67f..22eec3228 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,8 +1,8 @@
 image: nixos/nix:latest
 
 variables:
-  # Pinned 2020-03-28.
-  NIX_PATH: "nixpkgs=https://github.com/NixOS/nixpkgs/archive/05f0934825c2a0750d4888c4735f9420c906b388.tar.gz"
+  # Pinned 2020-09-11.
+  NIX_PATH: "nixpkgs=https://github.com/NixOS/nixpkgs/archive/6d4b93323e7f78121f8d6db6c59f3889aa1dd931.tar.gz"
 
 stages:
   - test