diff --git a/tests/test_utils.py b/tests/test_utils.py
index 1e394be..f9ba56d 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -1,7 +1,7 @@
 """Tests for utility modules."""
 
+import threading
 import time
-from unittest.mock import patch
 
 from data.oui import get_manufacturer
 from utils.cleanup import DataStore
@@ -93,35 +93,54 @@ class TestDataStoreCleanup:
         assert "new" in store
 
     def test_cleanup_does_not_delete_refreshed_entry(self):
-        """An entry refreshed after the cleanup snapshot must survive cleanup()."""
+        """Entry refreshed after the snapshot is taken must survive deletion re-validation."""
         store = DataStore(max_age_seconds=0.05, name="test")
         store.set("key", "old")
         time.sleep(0.06)  # expire it
 
-        # Mock time.time to return different values on successive calls.
-        # This simulates the scenario where cleanup() snapshots the timestamp,
-        # then between snapshot and deletion a refresh happens (timestamp updates),
-        # and the re-validation check uses a different time value.
-        call_sequence = iter(
-            [
-                time.time() - 1.0,  # cleanup() first call: now = old time, so "key" appears expired
-                time.time() - 1.0,  # re-validation: now = same time, still expired... but wait
-            ]
-        )
+        real_lock = store._lock
+        snapshot_done = threading.Event()
+        ok_to_delete = threading.Event()
+        exit_count = [0]
 
-        original_time = time.time
+        class PauseLock:
+            def acquire(self, *a, **kw):
+                return real_lock.acquire(*a, **kw)
 
-        def mocked_time():
-            try:
-                return next(call_sequence)
-            except StopIteration:
-                # After we've used the mock sequence, return current time
-                return original_time()
+            def release(self):
+                real_lock.release()
 
-        with patch("utils.cleanup.time.time", mocked_time):
-            # Just before cleanup, refresh the key so it has a fresh timestamp
-            store.set("key", "refreshed")
-            removed = store.cleanup()
+            def __enter__(self):
+                self.acquire()
+                return self
 
-        assert removed == 0, "Entry refreshed before cleanup must survive"
-        assert "key" in store
+            def __exit__(self, *a):
+                self.release()
+                exit_count[0] += 1
+                if exit_count[0] == 1:
+                    snapshot_done.set()
+                    ok_to_delete.wait(timeout=2.0)
+
+        store._lock = PauseLock()
+
+        result = [None]
+
+        def run():
+            result[0] = store.cleanup()
+
+        t = threading.Thread(target=run, daemon=True)
+        t.start()
+
+        snapshot_done.wait(timeout=2.0)
+
+        # Inject refresh using real_lock directly (bypasses PauseLock)
+        with real_lock:
+            store.data["key"] = "refreshed"
+            store.timestamps["key"] = time.time()
+
+        ok_to_delete.set()
+        t.join(timeout=2.0)
+        store._lock = real_lock
+
+        assert result[0] == 0, "Re-validation guard must prevent deletion of refreshed entry"
+        assert store.get("key") == "refreshed"