diff --git a/assets/shell.nix b/assets/shell.nix
index 1c485cec..942ce016 100644
--- a/assets/shell.nix
+++ b/assets/shell.nix
@@ -2,7 +2,7 @@
   (
     let lock = builtins.fromJSON (builtins.readFile ./flake.lock); in
     fetchTarball {
-      url = lock.nodes.flake-compat.locked.url;
+      url = lock.nodes.flake-compat.locked.url or "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
       sha256 = lock.nodes.flake-compat.locked.narHash;
     }
   )