diff --git a/nixos/lib/testing-python.nix b/nixos/lib/testing-python.nix
index 070a3a7ddc2..e95ebe16eca 100644
--- a/nixos/lib/testing-python.nix
+++ b/nixos/lib/testing-python.nix
@@ -187,11 +187,13 @@ rec {
           --set testScript "$out/test-script" \
           --set vlans '${toString vlans}'
 
-        ln -s ${testDriver}/bin/nixos-test-driver $out/bin/nixos-run-vms
-        wrapProgram $out/bin/nixos-run-vms \
-          --set startScripts "''${vmStartScripts[*]}" \
-          --set testScript "${pkgs.writeText "start-all" "start_all(); join_all();"}" \
-          --set vlans '${toString vlans}'
+        ${lib.optionalString (testScript == "") ''
+          ln -s ${testDriver}/bin/nixos-test-driver $out/bin/nixos-run-vms
+          wrapProgram $out/bin/nixos-run-vms \
+            --set startScripts "''${vmStartScripts[*]}" \
+            --set testScript "${pkgs.writeText "start-all" "start_all(); join_all();"}" \
+            --set vlans '${toString vlans}'
+        ''}
       '');
 
   # Make a full-blown test