diff --git a/pkgs/tools/package-management/nix/unstable.nix b/pkgs/tools/package-management/nix/unstable.nix
index a54661143583..8b6ccb787be9 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-1.1pre2718_8da6772";
+  name = "nix-1.1pre2723_1aba0bf";
 
   src = fetchurl {
-    url = "http://hydra.nixos.org/build/2727338/download/4/${name}.tar.bz2";
-    sha256 = "99466467b01102d8a2e1022283259ac490427b9a45c3c4784af027977014d7c5";
+    url = "http://hydra.nixos.org/build/2746466/download/4/${name}.tar.bz2";
+    sha256 = "06224ecbde09124eea25bfcafcb06637457bc6ac9a9e332d84e9eaf561599160";
   };
 
   buildNativeInputs = [ perl pkgconfig ];