diff --git a/third_party/nixpkgs/default.nix b/third_party/nixpkgs/default.nix
index 7c21ff9df..b7cc3fc74 100644
--- a/third_party/nixpkgs/default.nix
+++ b/third_party/nixpkgs/default.nix
@@ -33,6 +33,10 @@ let
         # Forbids our meta.ci attribute
         # https://github.com/NixOS/nixpkgs/pull/191171#issuecomment-1260650771
         checkMeta = false;
+        permittedInsecurePackages = [
+          # only used inside tests
+          "nix-2.3.18"
+        ];
       };
 
     inherit localSystem crossSystem;
diff --git a/third_party/sources/sources.json b/third_party/sources/sources.json
index 7df94b273..083b5a9b1 100644
--- a/third_party/sources/sources.json
+++ b/third_party/sources/sources.json
@@ -97,10 +97,10 @@
         "homepage": "",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "adaa24fbf46737f3f1b5497bf64bae750f82942e",
-        "sha256": "0mmcni35fxs87fnhavfprspczgnnkxyizy8a4x57y98y76c4q4da",
+        "rev": "d5b6a55e1702a6d0be95b4e03e617d418ad48456",
+        "sha256": "0ciqs1qdqxd7fmgzx7qicr4aghbdm8ir22wzpwf87bsck659wv9n",
         "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/adaa24fbf46737f3f1b5497bf64bae750f82942e.tar.gz",
+        "url": "https://github.com/NixOS/nixpkgs/archive/d5b6a55e1702a6d0be95b4e03e617d418ad48456.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "nixpkgs-stable": {