diff --git a/main.nix b/main.nix
index 1525462..95174c7 100644
--- a/main.nix
+++ b/main.nix
@@ -28,6 +28,6 @@ in
       constituents = builtins.attrValues jobs;
     };
     extended-tests = pkgs.runCommand "extended-tests" {
-      propagatedBuildInputs = [pkgs.python3.withPackages(ps: [artiqpkgs.artiq artiqpkgs.artiq-board-kc705-nist_clock])];
+      propagatedBuildInputs = [(pkgs.python3.withPackages(ps: [artiqpkgs.artiq artiqpkgs.artiq-board-kc705-nist_clock]))];
     } "cp ${./extended-tests.py} $out;";
   }