diff --git a/v1/nix/modules/flake-parts/writers.nix b/v1/nix/modules/flake-parts/writers.nix
index fc50e8cc..e1d17a49 100644
--- a/v1/nix/modules/flake-parts/writers.nix
+++ b/v1/nix/modules/flake-parts/writers.nix
@@ -19,6 +19,7 @@
     - PATH only contains exactly the packages passed via the PATH arg
     - NIX_PATH is set to the path of the current `pkgs`
     - TMPDIR is set up and cleaned up even if the script fails
+    - out, if set, is kept as-is
     - all environment variables are unset, except:
     - the ones listed in `keepVars` below
     - ones listed via the KEEP_VARS variable
@@ -67,6 +68,7 @@
         "no_proxy"
 
         # We want to keep out own variables as well
+        "out"
         "IMPURE"
         "KEEP_VARS"
         "NIX_PATH"