diff --git a/pkgs/tools/package-management/nix/unstable.nix b/pkgs/tools/package-management/nix/unstable.nix
index 921e902e061..8235565f7a6 100644
--- a/pkgs/tools/package-management/nix/unstable.nix
+++ b/pkgs/tools/package-management/nix/unstable.nix
@@ -5,11 +5,11 @@
 }:
 
 stdenv.mkDerivation rec {
-  name = "nix-1.0pre30305";
+  name = "nix-1.0pre30457";
 
   src = fetchurl {
-    url = "http://hydra.nixos.org/build/1524522/download/4/${name}.tar.bz2";
-    sha256 = "917b22e350e1aee99e465c2df0037ce224dca625e588bb0005e3048fe07cdb9a";
+    url = "http://hydra.nixos.org/build/1554072/download/4/${name}.tar.bz2";
+    sha256 = "d95b0577c1ab9646f2b5f0f37a96e5822013cd8046265c5608ea8acfab7ba602";
   };
 
   buildNativeInputs = [ perl pkgconfig ];