diff --git a/extended-tests.py b/extended-tests.py
index d98e284..4556e71 100644
--- a/extended-tests.py
+++ b/extended-tests.py
@@ -1,14 +1,16 @@
 import json
-import bz2
 import sys
+import subprocess
 
-with open(sys.argv[1], "r") as f:
-    hydra_json = json.load(f)
+with open(sys.argv[1], "r") as hydra_json_file:
+    hydra_json = json.load(hydra_json_file)
 
 drv = hydra_json["drvPath"]
 assert drv.startswith("/nix/store/")
 drv = drv[len("/nix/store/"):]
-hydra_log = "/var/lib/hydra/build-logs/" + drv[:2] + "/" + drv[2:] + ".bz2"
+hydra_log = "/var/lib/hydra/build-logs/" + drv[:2] + "/" + drv[2:]
 
-with bz2.BZ2File(hydra_log, "w") as f:
-    f.write(b"hack successful")
+with open(hydra_log, "w") as log:
+    def run(*args):
+        subprocess.run(args, stdout=log, stderr=log).check_returncode()
+    run("artiq_flash", "-t", "kc705", "-V", "nist_clock")