diff --git a/nixos/lib/testing-python.nix b/nixos/lib/testing-python.nix
index 3d09be3b6cd5..a7f6d7926514 100644
--- a/nixos/lib/testing-python.nix
+++ b/nixos/lib/testing-python.nix
@@ -155,7 +155,7 @@ in rec {
             --add-flags "''${vms[*]}" \
             ${lib.optionalString enableOCR
               "--prefix PATH : '${ocrProg}/bin:${imagemagick_tiff}/bin'"} \
-            --run "export testScript=\"\$(cat $out/test-script)\"" \
+            --run "export testScript=\"\$(${coreutils}/bin/cat $out/test-script)\"" \
             --set VLANS '${toString vlans}'
           ln -s ${testDriver}/bin/nixos-test-driver $out/bin/nixos-run-vms
           wrapProgram $out/bin/nixos-run-vms \