diff --git a/flake.nix b/flake.nix
index ff2780a1..13781ea9 100644
--- a/flake.nix
+++ b/flake.nix
@@ -213,7 +213,7 @@
             mobile = (import "${mobile-nixos}/overlay/overlay.nix");
             uninsane = uninsane-dot-org.overlays.default;
             # TODO: why do i have to use `self.inputs.nix-fast-build` instead of just `nix-fast-build` here?
-            nix-fast-build = (_: prev: self.inputs.nix-fast-build.packages."${prev.stdenv.system}");
+            nix-fast-build = (_: prev: self.inputs.nix-fast-build.packages."${prev.stdenv.system}" or {});
           in
             (mobile final prev)
             // (nix-fast-build final prev)