diff --git a/pkgs/build-support/fetchurl/default.nix b/pkgs/build-support/fetchurl/default.nix
index 0fcbf2f3d0da..77a589a26f17 100644
--- a/pkgs/build-support/fetchurl/default.nix
+++ b/pkgs/build-support/fetchurl/default.nix
@@ -13,6 +13,7 @@ let
     stdenv.mkDerivation ({
       name = "mirrors-list";
       builder = ./write-mirror-list.sh;
+      preferLocalBuilding = true;
     } // mirrors);
 
   # Names of the master sites that are mirrored (i.e., "sourceforge",