diff --git a/tests/README.md b/tests/README.md
index f5bbbc41..11a87022 100644
--- a/tests/README.md
+++ b/tests/README.md
@@ -73,7 +73,7 @@ also by Ansible's `osx_setup.yml`.
     used to target this account, the parent session requires a TTY and the
     account password must be entered.
 
-`mitogen__user1` .. `mitogen__user21`
+`mitogen__user1` .. `mitogen__user5`
     These accounts do not have passwords set. They exist to test the Ansible
     interpreter recycling logic.
 
diff --git a/tests/image_prep/_user_accounts.yml b/tests/image_prep/_user_accounts.yml
index 0167a09f..0c1f6045 100644
--- a/tests/image_prep/_user_accounts.yml
+++ b/tests/image_prep/_user_accounts.yml
@@ -9,8 +9,12 @@
   strategy: mitogen_linear
   become: true
   vars:
+    distro: "{{ansible_distribution}}"
+    ver: "{{ansible_distribution_major_version}}"
+
     special_users:
       - has_sudo
+      - has_sudo_nopw
       - has_sudo_pubkey
       - pw_required
       - readonly_homedir
@@ -19,10 +23,10 @@
       - slow_user
       - webapp
 
-    groups:
-      - has_sudo: ['mitogen__group', '{{sudo_group[distro]}}']
-      - has_sudo_pubkey: ['mitogen__group', '{{sudo_group[distro]}}']
-      - has_sudo_nopw: ['mitogen__group', 'mitogen__sudo_nopw']
+    user_groups:
+      has_sudo: ['mitogen__group', '{{sudo_group[distro]}}']
+      has_sudo_pubkey: ['mitogen__group', '{{sudo_group[distro]}}']
+      has_sudo_nopw: ['mitogen__group', 'mitogen__sudo_nopw']
 
     normal_users: "{{
       lookup('sequence', 'start=1 end=5 format=user%d', wantlist=True)
@@ -53,14 +57,14 @@
       - user:
           name: "mitogen__{{item}}"
           shell: /bin/bash
-          groups: "{{groups[item]|default(['mitogen__group'])}}"
+          groups: "{{user_groups[item]|default(['mitogen__group'])}}"
           password: "{{ (item + '_password') | password_hash('sha256') }}"
         loop: "{{all_users}}"
         when: ansible_system != 'Darwin'
       - user:
           name: "mitogen__{{item}}"
           shell: /bin/bash
-          groups: "{{groups[item]|default(['mitogen__group'])}}"
+          groups: "{{user_groups[item]|default(['mitogen__group'])}}"
           password: "{{item}}_password"
         loop: "{{all_users}}"
         when: ansible_system == 'Darwin'
diff --git a/tests/image_prep/build_docker_images.py b/tests/image_prep/build_docker_images.py
index 44c4e2dd..c085d29e 100755
--- a/tests/image_prep/build_docker_images.py
+++ b/tests/image_prep/build_docker_images.py
@@ -23,9 +23,11 @@ def sh(s, *args):
 
 label_by_id = {}
 
-for base_image, label in [('debian:stretch', 'debian'),
-                          ('centos:6', 'centos6'),
-                          ('centos:7', 'centos7')]:
+for base_image, label in [
+        ('debian:stretch', 'debian'),
+        ('centos:6', 'centos6'),
+        ('centos:7', 'centos7')
+    ]:
     args = sh('docker run --rm -it -d -h mitogen-%s %s /bin/bash',
               label, base_image)
     container_id = subprocess.check_output(args).strip()