diff --git a/tests/test_serverless/test_utils/test_download.py b/tests/test_serverless/test_utils/test_download.py
index bc04db95..b7533f5c 100644
--- a/tests/test_serverless/test_utils/test_download.py
+++ b/tests/test_serverless/test_utils/test_download.py
@@ -95,10 +95,14 @@ def test_download_files_from_urls(self, mock_open_file, mock_get, mock_makedirs)
 
         self.assertEqual(len(downloaded_files), len(urls))
 
-        for index, url in enumerate(urls):
-            # Check that the url was called with SyncClientSession.get
-            self.assertIn(url, mock_get.call_args_list[index][0])
-
+        # Downloads run in parallel threads, so the order of get() calls is
+        # non-deterministic; assert the set of requested URLs instead of order.
+        requested_urls = {call.args[0] for call in mock_get.call_args_list}
+        self.assertEqual(requested_urls, set(urls))
+
+        # executor.map preserves input order in results, so downloaded_files
+        # still aligns positionally with urls.
+        for index in range(len(urls)):
             # Check that the file has the correct extension
             self.assertTrue(downloaded_files[index].endswith(".jpg"))
 
diff --git a/tests/test_serverless/test_worker.py b/tests/test_serverless/test_worker.py
index e1fd743f..28544add 100644
--- a/tests/test_serverless/test_worker.py
+++ b/tests/test_serverless/test_worker.py
@@ -6,7 +6,7 @@
 import os
 import sys
 from unittest import mock
-from unittest.mock import patch, mock_open, Mock, MagicMock
+from unittest.mock import patch, mock_open, Mock, MagicMock, AsyncMock
 
 from unittest import IsolatedAsyncioTestCase
 import nest_asyncio
@@ -182,6 +182,16 @@ class TestRunWorker(IsolatedAsyncioTestCase):
     async def asyncSetUp(self):
         os.environ["RUNPOD_WEBHOOK_GET_JOB"] = "https://test.com"
 
+        # Fitness checks probe real host resources (e.g. available memory) and
+        # exit the process when unmet; they have dedicated coverage in
+        # tests/test_serverless/test_modules/test_fitness/. Stub them here so
+        # run_worker tests are deterministic regardless of host state.
+        fitness_patcher = patch(
+            "runpod.serverless.worker.run_fitness_checks", new=AsyncMock()
+        )
+        fitness_patcher.start()
+        self.addCleanup(fitness_patcher.stop)
+
         # Set up the config
         self.config = {
             "handler": MagicMock(),