diff --git a/ofborg/src/tasks/eval/nixpkgs.rs b/ofborg/src/tasks/eval/nixpkgs.rs
index b126acb4..0ab93e5b 100644
--- a/ofborg/src/tasks/eval/nixpkgs.rs
+++ b/ofborg/src/tasks/eval/nixpkgs.rs
@@ -467,6 +467,14 @@ impl<'a> EvaluationStrategy for NixpkgsStrategy<'a> {
                 ],
                 self.nix.clone(),
             ),
+            EvalChecker::new(
+                "ct",
+                nix::Operation::Unknown { program: "nix-shell".to_owned() },
+                vec![
+                    String::from("./ct"),
+                ],
+                self.nix.clone(),
+            ),
             EvalChecker::new(
                 "nixos",
                 nix::Operation::Instantiate,