diff --git a/.ci/localhost_ansible_tests.py b/.ci/localhost_ansible_tests.py
index 11b1faa1..f9465899 100755
--- a/.ci/localhost_ansible_tests.py
+++ b/.ci/localhost_ansible_tests.py
@@ -44,7 +44,7 @@ with ci_lib.Fold('machine_prep'):
 
     if os.path.expanduser('~mitogen__user1') == '~mitogen__user1':
         os.chdir(IMAGE_PREP_DIR)
-        run("ansible-playbook -i localhost, _user_accounts.yml")
+        run("ansible-playbook -c local -i localhost, _user_accounts.yml")
 
 
 with ci_lib.Fold('ansible'):
diff --git a/tests/image_prep/ansible.cfg b/tests/image_prep/ansible.cfg
index 8a8c47fa..60f2975e 100644
--- a/tests/image_prep/ansible.cfg
+++ b/tests/image_prep/ansible.cfg
@@ -4,3 +4,4 @@ strategy_plugins = ../../ansible_mitogen/plugins/strategy
 retry_files_enabled = false
 display_args_to_stdout = True
 no_target_syslog = True
+host_key_checking = False