diff --git a/flake.nix b/flake.nix
index a77509c7d..01680ed10 100644
--- a/flake.nix
+++ b/flake.nix
@@ -407,6 +407,57 @@
             touch $out
             '';
         };
+        kc705-hitl = pkgs.stdenvNoCC.mkDerivation {
+          name = "kc705-hitl";
+
+          __networked = true;  # compatibility with old patched Nix
+          # breaks hydra, https://github.com/NixOS/hydra/issues/1216
+          #__impure = true;     # Nix 2.8+
+
+          buildInputs = [
+            (pkgs.python3.withPackages(ps: with packages.x86_64-linux; [ artiq ps.paramiko ]))
+            pkgs.llvm_14
+            pkgs.openssh
+            packages.x86_64-linux.openocd-bscanspi  # for the bscanspi bitstreams
+          ];
+          phases = [ "buildPhase" ];
+          buildPhase =
+            ''
+            export HOME=`mktemp -d`
+            mkdir $HOME/.ssh
+            cp /opt/hydra_id_ed25519 $HOME/.ssh/id_ed25519
+            cp /opt/hydra_id_ed25519.pub $HOME/.ssh/id_ed25519.pub
+            echo "rpi-1 ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIACtBFDVBYoAE4fpJCTANZSE0bcVpTR3uvfNvb80C4i5" > $HOME/.ssh/known_hosts
+            chmod 600 $HOME/.ssh/id_ed25519
+            LOCKCTL=$(mktemp -d)
+            mkfifo $LOCKCTL/lockctl
+
+            cat $LOCKCTL/lockctl | ${pkgs.openssh}/bin/ssh \
+              -i $HOME/.ssh/id_ed25519 \
+              -o UserKnownHostsFile=$HOME/.ssh/known_hosts \
+              rpi-1 \
+              'mkdir -p /tmp/board_lock && flock /tmp/board_lock/kc705-1 -c "echo Ok; cat"' \
+            | (
+              # End remote flock via FIFO
+              atexit_unlock() {
+                echo > $LOCKCTL/lockctl
+              }
+              trap atexit_unlock EXIT
+
+              # Read "Ok" line when remote successfully locked
+              read LOCK_OK
+
+              artiq_flash -t kc705 -H rpi-1 -d ${packages.x86_64-linux.artiq-board-kc705-nist_clock}
+              sleep 30
+
+              export ARTIQ_ROOT=`python -c "import artiq; print(artiq.__path__[0])"`/examples/kc705_nist_clock
+              export ARTIQ_LOW_LATENCY=1
+              python -m unittest discover -v artiq.test.coredevice
+            )
+
+            touch $out
+            '';
+        };
       };
     };