diff --git a/ansible/group_vars/all/semaphore.yml b/ansible/group_vars/all/semaphore.yml
index 2c3241f..20aeef0 100644
--- a/ansible/group_vars/all/semaphore.yml
+++ b/ansible/group_vars/all/semaphore.yml
@@ -104,6 +104,9 @@ semaphore_config:
         # from the playbook's directory as I first assumed). Path is
         # therefore relative to repo root, not playbook dir.
         ANSIBLE_ROLES_PATH: "ansible/roles"
+        # Collections are installed by the semaphore role into a host-side
+        # directory bind-mounted into the container at this path.
+        ANSIBLE_COLLECTIONS_PATH: "/opt/ansible-collections"
 
   templates:
     - name: "day0_linux_baseline"