diff --git a/ansible/group_vars/all/semaphore.yml b/ansible/group_vars/all/semaphore.yml
index 02e64bd..22d4b62 100644
--- a/ansible/group_vars/all/semaphore.yml
+++ b/ansible/group_vars/all/semaphore.yml
@@ -100,6 +100,11 @@ semaphore_config:
       env:
         ANSIBLE_HOST_KEY_CHECKING: "False"
         ANSIBLE_FORCE_COLOR: "True"
+        # Semaphore runs ansible-playbook from the playbook's directory
+        # (ansible/playbooks/), which doesn't pick up ansible.cfg from
+        # the parent ansible/ dir. Point roles_path at the canonical
+        # location relative to that working directory.
+        ANSIBLE_ROLES_PATH: "../roles"
 
   templates:
     - name: "day0_linux_baseline"