diff --git a/tox.ini b/tox.ini
index 23a204aa8..9c1d8af96 100644
--- a/tox.ini
+++ b/tox.ini
@@ -30,9 +30,10 @@ commands =
   doc8 -e .rst specs/ doc/source/ CONTRIBUTING.rst HACKING.rst README.rst
   bash tools/flake8wrap.sh {posargs}
   # The following bandit tests are being skipped:
-  # B303 - Use of insecure MD2, MD4, or MD5 hash function.
+  # B303 - Use of insecure MD2, MD4, or MD5 hash function for python<3.9
+  # B324 - Prohibit list calls: md5, sha1 for python>=3.9
   # B604 - unction call with shell=True parameter identified, possible security issue.
-  bandit -r zun -x tests -n5 -ll --skip B303,B604
+  bandit -r zun -x tests -n5 -ll --skip B303,B324,B604
 
 [testenv:venv]
 basepython = python3
diff --git a/zun/container/docker/driver.py b/zun/container/docker/driver.py
index a8625c970..fe8a96a9b 100644
--- a/zun/container/docker/driver.py
+++ b/zun/container/docker/driver.py
@@ -988,7 +988,7 @@ class DockerDriver(driver.BaseDriver, driver.ContainerDriver,
             blk_stats = res['blkio_stats']['io_service_bytes_recursive']
             io_read = 0
             io_write = 0
-            for item in blk_stats:
+            for item in (blk_stats or []):
                 if 'Read' == item['op']:
                     io_read = io_read + item['value']
                 if 'Write' == item['op']: