diff --git a/.nix/fallback-config.nix b/.nix/fallback-config.nix
index 110bf6d..96f9ae0 100644
--- a/.nix/fallback-config.nix
+++ b/.nix/fallback-config.nix
@@ -1,3 +1,8 @@
+let
+  latest = builtins.fetchTarball {
+    url = "https://github.com/rocq-prover/rocq/archive/refs/heads/master.tar.gz";
+  };
+in
 with (import (import ./nixpkgs.nix) {}).lib;
 {
   ## DO NOT CHANGE THIS
@@ -30,8 +35,8 @@ with (import (import ./nixpkgs.nix) {}).lib;
       coqPackages.coq.override.version = v;
     })) // {
     master = {
-      rocqPackages.rocq-core.override.version = "master";
-      coqPackages.coq.override.version = "master";
+      rocqPackages.rocq-core.override.version = latest;
+      coqPackages.coq.override.version = latest;
       coqPackages.heq.job = false;
       coqPackages.stdlib.job = false;
     };
@@ -42,7 +47,7 @@ with (import (import ./nixpkgs.nix) {}).lib;
       rocqPackages.rocq-core.override.version = "9.1";
     };
     "rocq-master" = {
-      rocqPackages.rocq-core.override.version = "master";
+      rocqPackages.rocq-core.override.version = latest;
     };
   };
 
diff --git a/.nix/nixpkgs.nix b/.nix/nixpkgs.nix
index a00a3bd..cfc2f61 100644
--- a/.nix/nixpkgs.nix
+++ b/.nix/nixpkgs.nix
@@ -1,4 +1,4 @@
 fetchTarball {
-    url = "https://github.com/NixOS/nixpkgs/archive/d3244e63ff6db4c5e43e1af9ff3eeaa280345f5b.tar.gz";
-    sha256 = "1zz2zq5y3a12k6bc2kqvsar7ylg9zalvi5p16qcf4qc5pd4zvamc";
-  }
+  url = "https://github.com/stepbrobd/nixpkgs/archive/8cb974d050ab53228609758925b57e39832b4bf7.tar.gz";
+  sha256 = "0hbyk79q9bzr3db2914q1vqiwxms0gl1ddaysalpa1h341v58s81";
+}