diff --git a/aftltool.py b/aftltool.py
index b695d16..0fe2d07 100755
--- a/aftltool.py
+++ b/aftltool.py
@@ -1491,8 +1491,9 @@
       process_number: The number of the processes executing the function.
       submission_count: Number of total submissions to perform per
         process_count.
-      preserve_icp_images: Boolean to indicate if the generated vbmeta
-        image files with inclusion proofs should preserved.
+      preserve_icp_images: Boolean to indicate if the generated vbmeta image
+        files with inclusion proofs should be preserved in the temporary
+        directory.
       timeout: Duration in seconds before requests to the AFTL times out. A
         value of 0 or None means there will be no timeout.
       result_queue: Multiprocessing.Queue object for posting execution results.
@@ -1500,7 +1501,8 @@
     for count in range(0, submission_count):
       version_incremental = 'aftl_load_testing_{}_{}'.format(process_number,
                                                              count)
-      output_file = '{}_icp.img'.format(version_incremental)
+      output_file = os.path.join(tempfile.gettempdir(),
+                                 '{}_icp.img'.format(version_incremental))
       output = open(output_file, 'wb')
 
       # Instrumented section.
@@ -1543,6 +1545,7 @@
       submission_count: Number of total submissions to perform per
         process_count.
       stats_filename: Path to the stats file to write the raw execution data to.
+        If None, it will be written to the temp directory.
       preserve_icp_images: Boolean to indicate if the generated vbmeta
         image files with inclusion proofs should preserved.
       timeout: Duration in seconds before requests to the AFTL times out. A
@@ -1557,11 +1560,13 @@
       return False
 
     if not stats_filename:
-      stats_filename = 'load_test_p{}_s{}.csv'.format(process_count,
-                                                      submission_count)
+      stats_filename = os.path.join(
+          tempfile.gettempdir(),
+          'load_test_p{}_s{}.csv'.format(process_count, submission_count))
+
     stats_file = None
     try:
-      stats_file = open(stats_filename, 'w')
+      stats_file = open(stats_filename, 'wt')
       stats_file.write('start_time,end_time,execution_time,version_incremental,'
                        'result\n')
     except IOError as e:
diff --git a/aftltool_test.py b/aftltool_test.py
index b568dee..006deb9 100755
--- a/aftltool_test.py
+++ b/aftltool_test.py
@@ -31,6 +31,7 @@
 import os
 import struct
 import sys
+import tempfile
 import unittest
 
 import aftltool
@@ -728,25 +729,23 @@
 
   def test_verify_icp(self):
     """Tests verify_icp method."""
-    key_file = 'transparency_log_pub_key.pem'
-    with open(key_file, 'w') as f:
-      f.write(self.test_aftl_pub_key)
+    with tempfile.NamedTemporaryFile('wt+') as key_file:
+      key_file.write(self.test_aftl_pub_key)
+      key_file.flush()
 
-    # Valid ICP.
-    entry = aftltool.AftlIcpEntry()
-    entry.translate_response(self.test_tl_url_1, self.test_afi_resp)
-    self.assertTrue(entry.verify_icp(key_file))
+      # Valid ICP.
+      entry = aftltool.AftlIcpEntry()
+      entry.translate_response(self.test_tl_url_1, self.test_afi_resp)
+      self.assertTrue(entry.verify_icp(key_file.name))
 
-    # Invalid ICP where fw_info_leaf is not matching up with proofs.
-    # pylint: disable=protected-access
-    entry = aftltool.AftlIcpEntry()
-    entry.translate_response(self.test_tl_url_1, self.test_afi_resp)
-    fw_info_leaf_bytes = entry.fw_info_leaf._fw_info_leaf_bytes.replace(
-        b'ViNzEQS', b'1234567')
-    entry.fw_info_leaf._fw_info_leaf_bytes = fw_info_leaf_bytes
-    self.assertFalse(entry.verify_icp(key_file))
-
-    os.remove(key_file)
+      # Invalid ICP where fw_info_leaf is not matching up with proofs.
+      # pylint: disable=protected-access
+      entry = aftltool.AftlIcpEntry()
+      entry.translate_response(self.test_tl_url_1, self.test_afi_resp)
+      fw_info_leaf_bytes = entry.fw_info_leaf._fw_info_leaf_bytes.replace(
+          b'ViNzEQS', b'1234567')
+      entry.fw_info_leaf._fw_info_leaf_bytes = fw_info_leaf_bytes
+      self.assertFalse(entry.verify_icp(key_file.name))
 
   def test_verify_vbmeta_image(self):
     """Tests the verify_vbmeta_image method."""
@@ -1156,7 +1155,6 @@
     self.manufacturer_key = None
     self.set_up_environment()
 
-    self.output_filename = 'vbmeta_icp.img'
     self.transparency_log_config = aftltool.TransparencyLogConfig(
         self.aftl_host, self.aftl_pubkey, self.aftl_apikey)
 
@@ -1173,12 +1171,12 @@
     }
 
     self.info_icp_default_params = {
-        'vbmeta_image_path': self.output_filename,
+        'vbmeta_image_path': None,
         'output': io.StringIO()
     }
 
     self.verify_icp_default_params = {
-        'vbmeta_image_path': self.output_filename,
+        'vbmeta_image_path': None,
         'transparency_log_pub_keys': [self.aftl_pubkey],
         'output': io.StringIO()
     }
@@ -1195,24 +1193,6 @@
         'timeout': None
     }
 
-    self.load_test_stats_file_p1_s1 = 'load_test_p1_s1.csv'
-    self.load_test_stats_file_p2_p2 = 'load_test_p2_s2.csv'
-
-    self.files_to_cleanup = [
-        self.output_filename,
-        self.load_test_stats_file_p1_s1,
-        self.load_test_stats_file_p2_p2
-    ]
-
-  def tearDown(self):
-    """Tears down the test bed for the unit tests."""
-    for filename in self.files_to_cleanup:
-      try:
-        os.remove(filename)
-      except OSError:
-        pass
-    super(AftlTestCase, self).tearDown()
-
   def set_up_environment(self):
     """Sets up member variables for the particular test environment.
 
@@ -1355,22 +1335,25 @@
     aftl = self.get_aftl_implementation(self.test_afi_resp)
 
     # Make a VBmeta image with ICP.
-    with open(self.output_filename, 'wb') as output_file:
+    with tempfile.NamedTemporaryFile('wb+') as output_file:
       self.make_icp_default_params['output'] = output_file
       result = aftl.make_icp_from_vbmeta(**self.make_icp_default_params)
-    self.assertTrue(result)
+      output_file.flush()
+      self.assertTrue(result)
 
-    # Checks that there is 1 ICP.
-    aftl_image = aftl.get_aftl_image(self.output_filename)
-    self.assertEqual(aftl_image.image_header.icp_count, 1)
+      # Checks that there is 1 ICP.
+      aftl_image = aftl.get_aftl_image(output_file.name)
+      self.assertEqual(aftl_image.image_header.icp_count, 1)
 
-    # Verifies the generated image.
-    result = aftl.verify_image_icp(**self.verify_icp_default_params)
-    self.assertTrue(result)
+      # Verifies the generated image.
+      self.verify_icp_default_params['vbmeta_image_path'] = output_file.name
+      result = aftl.verify_image_icp(**self.verify_icp_default_params)
+      self.assertTrue(result)
 
-    # Prints the image details.
-    result = aftl.info_image_icp(**self.info_icp_default_params)
-    self.assertTrue(result)
+      # Prints the image details.
+      self.info_icp_default_params['vbmeta_image_path'] = output_file.name
+      result = aftl.info_image_icp(**self.info_icp_default_params)
+      self.assertTrue(result)
 
   def test_make_and_verify_icp_with_2_logs(self):
     """Tests make_icp_from_vbmeta, verify_image_icp & info_image_icp."""
@@ -1381,23 +1364,26 @@
         self.transparency_log_config, self.transparency_log_config]
 
     # Make a VBmeta image with ICP.
-    with open(self.output_filename, 'wb') as output_file:
+    with tempfile.NamedTemporaryFile('wb+') as output_file:
       self.make_icp_default_params['output'] = output_file
       result = aftl.make_icp_from_vbmeta(
           **self.make_icp_default_params)
+      output_file.flush()
       self.assertTrue(result)
 
-    # Checks that there are 2 ICPs.
-    aftl_image = aftl.get_aftl_image(self.output_filename)
-    self.assertEqual(aftl_image.image_header.icp_count, 2)
+      # Checks that there are 2 ICPs.
+      aftl_image = aftl.get_aftl_image(output_file.name)
+      self.assertEqual(aftl_image.image_header.icp_count, 2)
 
-    # Verifies the generated image.
-    result = aftl.verify_image_icp(**self.verify_icp_default_params)
-    self.assertTrue(result)
+      # Verifies the generated image.
+      self.verify_icp_default_params['vbmeta_image_path'] = output_file.name
+      result = aftl.verify_image_icp(**self.verify_icp_default_params)
+      self.assertTrue(result)
 
-    # Prints the image details.
-    result = aftl.info_image_icp(**self.info_icp_default_params)
-    self.assertTrue(result)
+      # Prints the image details.
+      self.info_icp_default_params['vbmeta_image_path'] = output_file.name
+      result = aftl.info_image_icp(**self.info_icp_default_params)
+      self.assertTrue(result)
 
   def test_info_image_icp(self):
     """Tests info_image_icp with vbmeta image with 2 ICP."""
@@ -1460,7 +1446,7 @@
     aftl = self.get_aftl_implementation(aftltool.AftlError('Comms error'))
     self.make_icp_default_params[
         'transparency_log_configs'][0].target = 'www.google.com:80'
-    with open(self.output_filename, 'wb') as output_file:
+    with tempfile.NamedTemporaryFile('wb+') as output_file:
       self.make_icp_default_params['output'] = output_file
       result = aftl.make_icp_from_vbmeta(
           **self.make_icp_default_params)
@@ -1474,7 +1460,7 @@
     # time of the transparency log per load test results in b/139407814#2 where
     # it was 3.43 seconds.
     self.make_icp_default_params['timeout'] = 1
-    with open(self.output_filename, 'wb') as output_file:
+    with tempfile.NamedTemporaryFile('wb+') as output_file:
       self.make_icp_default_params['output'] = output_file
       result = aftl.make_icp_from_vbmeta(
           **self.make_icp_default_params)
@@ -1484,14 +1470,18 @@
     """Tests load_test_aftl command with 1 process which does 1 submission."""
     aftl = self.get_aftl_implementation(self.test_afi_resp)
 
-    result = aftl.load_test_aftl(**self.load_test_aftl_default_params)
-    self.assertTrue(result)
+    with tempfile.TemporaryDirectory() as tmp_dir:
+      self.load_test_aftl_default_params[
+          'stats_filename'] = os.path.join(tmp_dir, 'load_test.csv')
+      result = aftl.load_test_aftl(**self.load_test_aftl_default_params)
+      self.assertTrue(result)
 
-    output = self.load_test_aftl_default_params['output'].getvalue()
-    self.assertRegex(output, 'Succeeded:.+?1\n')
-    self.assertRegex(output, 'Failed:.+?0\n')
+      output = self.load_test_aftl_default_params['output'].getvalue()
+      self.assertRegex(output, 'Succeeded:.+?1\n')
+      self.assertRegex(output, 'Failed:.+?0\n')
 
-    self.assertTrue(os.path.exists(self.load_test_stats_file_p1_s1))
+      self.assertTrue(os.path.exists(
+          self.load_test_aftl_default_params['stats_filename']))
 
   def test_load_test_multi_process_multi_submission(self):
     """Tests load_test_aftl command with 2 processes and 2 submissions each."""
@@ -1499,14 +1489,18 @@
 
     self.load_test_aftl_default_params['process_count'] = 2
     self.load_test_aftl_default_params['submission_count'] = 2
-    result = aftl.load_test_aftl(**self.load_test_aftl_default_params)
-    self.assertTrue(result)
+    with tempfile.TemporaryDirectory() as tmp_dir:
+      self.load_test_aftl_default_params[
+          'stats_filename'] = os.path.join(tmp_dir, 'load_test.csv')
+      result = aftl.load_test_aftl(**self.load_test_aftl_default_params)
+      self.assertTrue(result)
 
-    output = self.load_test_aftl_default_params['output'].getvalue()
-    self.assertRegex(output, 'Succeeded:.+?4\n')
-    self.assertRegex(output, 'Failed:.+?0\n')
+      output = self.load_test_aftl_default_params['output'].getvalue()
+      self.assertRegex(output, 'Succeeded:.+?4\n')
+      self.assertRegex(output, 'Failed:.+?0\n')
 
-    self.assertTrue(os.path.exists(self.load_test_stats_file_p2_p2))
+      self.assertTrue(os.path.exists(
+          self.load_test_aftl_default_params['stats_filename']))
 
   def test_load_test_invalid_grpc_service(self):
     """Tests load_test_aftl command with a host that does not support GRPC."""