diff --git a/tests/ansible/hosts/become_same_user.hosts b/tests/ansible/hosts/become_same_user.hosts
index a18b90d2..ac744ed7 100644
--- a/tests/ansible/hosts/become_same_user.hosts
+++ b/tests/ansible/hosts/become_same_user.hosts
@@ -1,3 +1,5 @@
+# code: language=ini
+# vim: syntax=dosini
 
 # become_same_user.yml
 bsu-joe ansible_user=joe
diff --git a/tests/ansible/hosts/connection_delegation.hosts b/tests/ansible/hosts/connection_delegation.hosts
index a22bd5df..4ae861b0 100644
--- a/tests/ansible/hosts/connection_delegation.hosts
+++ b/tests/ansible/hosts/connection_delegation.hosts
@@ -1,3 +1,4 @@
+# code: language=ini
 # vim: syntax=dosini
 
 # Connection delegation scenarios. It's impossible to connect to them, but their would-be
diff --git a/tests/ansible/hosts/default.hosts b/tests/ansible/hosts/default.hosts
index d40c3dd0..1bec0014 100644
--- a/tests/ansible/hosts/default.hosts
+++ b/tests/ansible/hosts/default.hosts
@@ -1,9 +1,12 @@
+# code: language=ini
 # vim: syntax=dosini
 
 # When running the tests outside CI, make a single 'target' host which is the
 # local machine. The ansible_user override is necessary since some tests want a
 # fixed ansible.cfg remote_user setting to test against.
-target ansible_host=localhost ansible_user="{{lookup('env', 'USER')}}"
+# FIXME Hardcoded by replacement in some CI runs https://github.com/mitogen-hq/mitogen/issues/1022
+#       and os.environ['USER'] is not populated on Azure macOS runners.
+target ansible_host=localhost ansible_user="{{ lookup('pipe', 'whoami') }}"
 
 [test-targets]
 target
diff --git a/tests/ansible/hosts/k3.hosts b/tests/ansible/hosts/k3.hosts
index 34e1ff95..b210164b 100644
--- a/tests/ansible/hosts/k3.hosts
+++ b/tests/ansible/hosts/k3.hosts
@@ -1,3 +1,4 @@
+# code: language=ini
 # vim: syntax=dosini
 
 # Used for manual testing.
diff --git a/tests/ansible/hosts/localhost.hosts b/tests/ansible/hosts/localhost.hosts
index 41af412e..e42221e7 100644
--- a/tests/ansible/hosts/localhost.hosts
+++ b/tests/ansible/hosts/localhost.hosts
@@ -1,3 +1,4 @@
+# code: language=ini
 # vim: syntax=dosini
 
 # issue #511, #536: we must not define an explicit localhost, as some
diff --git a/tests/ansible/hosts/transport_config.hosts b/tests/ansible/hosts/transport_config.hosts
index 7d7b526a..32f5f61b 100644
--- a/tests/ansible/hosts/transport_config.hosts
+++ b/tests/ansible/hosts/transport_config.hosts
@@ -1,3 +1,6 @@
+# code: language=ini
+# vim: syntax=dosini
+
 # integration/transport_config
 # Hosts with twiddled configs that need to be checked somehow.