diff --git a/openpilot/starpilot/flm/live_tracking_bootstrap_producer.py b/openpilot/starpilot/flm/live_tracking_bootstrap_producer.py
index ff4a3e6217..ed2f0126f2 100644
--- a/openpilot/starpilot/flm/live_tracking_bootstrap_producer.py
+++ b/openpilot/starpilot/flm/live_tracking_bootstrap_producer.py
@@ -321,6 +321,7 @@ class ResponseSnapshotProcess:
         if ctypes.CDLL(None).prctl(1, signal.SIGKILL, 0, 0, 0) != 0 or os.getppid() != parent:
           os._exit(1)
         os.sched_setscheduler(0, os.SCHED_OTHER, os.sched_param(0))
+        os.nice(10)
         soft, hard = resource.getrlimit(resource.RLIMIT_CPU)
         limit = min([30] + [x for x in (soft, hard) if x >= 0])
         resource.setrlimit(resource.RLIMIT_CPU, (limit, hard))
diff --git a/openpilot/starpilot/flm/tests/test_snapshot_priority.py b/openpilot/starpilot/flm/tests/test_snapshot_priority.py
new file mode 100644
index 0000000000..b7173ae42f
--- /dev/null
+++ b/openpilot/starpilot/flm/tests/test_snapshot_priority.py
@@ -0,0 +1,38 @@
+"""Frozen snapshot preparation stays below its normal-priority receiver."""
+import json
+import subprocess
+import sys
+
+import pytest
+
+
+@pytest.mark.skipif(not sys.platform.startswith('linux'), reason='Production fork/scheduler path is Linux')
+def test_actual_snapshot_child_runs_below_receiver_and_is_reaped():
+  code = '''
+import json,os,resource,time
+from openpilot.starpilot.flm.live_tracking_bootstrap_producer import ResponseSnapshotProcess
+os.sched_setscheduler(0,os.SCHED_OTHER,os.sched_param(0))
+os.setpriority(os.PRIO_PROCESS,0,0)
+job=ResponseSnapshotProcess()
+try:
+ def prepare():
+  return {'nice':os.getpriority(os.PRIO_PROCESS,0),'scheduler':os.sched_getscheduler(0),
+          'cpu':resource.getrlimit(resource.RLIMIT_CPU)[0]}
+ stamp=time.monotonic_ns()
+ assert job.submit_preparation(prepare,token='priority-check',epoch=1,now_ns=stamp)
+ deadline=time.monotonic()+3
+ result=None
+ while job.pid is not None and time.monotonic()<deadline:
+  result=job.poll(token='priority-check',now_ns=time.monotonic_ns())
+  time.sleep(.005)
+ assert job.pid is None and job.fd is None
+ assert result is not None and result['nice']==10 and result['scheduler']==os.SCHED_OTHER,result
+ assert 0<result['cpu']<=30
+ assert os.getpriority(os.PRIO_PROCESS,0)==0
+ print(json.dumps(result))
+finally:
+ job.close()
+'''
+  result = subprocess.run([sys.executable, '-B', '-c', code], capture_output=True, text=True, timeout=8)
+  assert result.returncode == 0, result.stdout + result.stderr
+  assert json.loads(result.stdout)['nice'] == 10
diff --git a/prebuilt.json b/prebuilt.json
index 80bd5e75ba..cbeadd81b0 100644
--- a/prebuilt.json
+++ b/prebuilt.json
@@ -1 +1 @@
-{"protected_inventory_sha256": "5a275a8b8129e4e7aaab27ee02fbdaf7bb99d058b3f28dc7059125363b835ad1", "schema_version": 1}
+{"protected_inventory_sha256": "80994a1f575e185031b830d43d083e8f12bbd01f0963c24f5c862022eb1b90de", "schema_version": 1}