diff --git a/tests/ansible/osx_setup.yml b/tests/ansible/osx_setup.yml
index 582dd280..9482d25b 100644
--- a/tests/ansible/osx_setup.yml
+++ b/tests/ansible/osx_setup.yml
@@ -26,6 +26,13 @@
         - mitogen__pw_required
         - mitogen__require_tty_pw_required
 
+    - name: Create Mitogen test users
+      user:
+        name: "mitogen__user{{item}}"
+        shell: /bin/bash
+        password: mitogen__password
+      with_sequence: start=1 end=21
+
     - name: Hide test users from login window.
       shell: >
         defaults
@@ -38,6 +45,15 @@
         - mitogen__pw_required
         - mitogen__require_tty_pw_required
 
+    - name: Hide test users from login window.
+      shell: >
+        defaults
+        write
+        /Library/Preferences/com.apple.loginwindow
+        HiddenUsersList
+        -array-add 'mitogen__user{{item}}'
+      with_sequence: start=1 end=21
+
     - name: Require a TTY for two accounts
       lineinfile:
         path: /etc/sudoers
@@ -61,3 +77,9 @@
         line: "{{lookup('pipe', 'whoami')}} ALL = ({{item}}) NOPASSWD:ALL"
       with_items:
         - mitogen__require_tty
+
+    - name: Allow passwordless for many accounts
+      lineinfile:
+        path: /etc/sudoers
+        line: "{{lookup('pipe', 'whoami')}} ALL = (mitogen__user{{item}}) NOPASSWD:ALL"
+      with_sequence: start=1 end=21
diff --git a/tests/build_docker_image.py b/tests/build_docker_image.py
index 02172e04..9a8a057c 100755
--- a/tests/build_docker_image.py
+++ b/tests/build_docker_image.py
@@ -27,7 +27,8 @@ RUN \
     ( echo 'has-sudo-pubkey:y' | chpasswd; ) && \
     ( echo 'has-sudo-nopw:y' | chpasswd; ) && \
     mkdir ~has-sudo-pubkey/.ssh && \
-    { echo '#!/bin/bash\nexec strace -ff -o /tmp/pywrap$$.trace python2.7 "$@"' > /usr/local/bin/pywrap; chmod +x /usr/local/bin/pywrap; }
+    { echo '#!/bin/bash\nexec strace -ff -o /tmp/pywrap$$.trace python2.7 "$@"' > /usr/local/bin/pywrap; chmod +x /usr/local/bin/pywrap; } && \
+    { for i in `seq 1 21`; do useradd -s /bin/bash -m mitogen__user$i; done; }
 
 COPY data/docker/has-sudo-pubkey.key.pub /home/has-sudo-pubkey/.ssh/authorized_keys
 RUN \