diff --git a/pkgs/tools/compression/xz/default.nix b/pkgs/tools/compression/xz/default.nix
index 05cc672ab15..8d02e926e57 100644
--- a/pkgs/tools/compression/xz/default.nix
+++ b/pkgs/tools/compression/xz/default.nix
@@ -13,7 +13,7 @@ stdenv.mkDerivation rec {
   doCheck = true;
 
   # In stdenv-linux, prevent a dependency on bootstrap-tools.
-  preConfigure = "unset CONFIG_SHELL";
+  preConfigure = "CONFIG_SHELL=/bin/sh";
 
   postInstall = "rm -rf $out/share/doc";