diff --git a/.travis.yml b/.travis.yml
index 8a28a0a..0184a43 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,11 +11,19 @@ install:
   - pip install ansible
 
   # Add ansible.cfg to pick up roles path.
-  - "printf '[defaults]\nroles_path = ../\n' > ansible.cfg"
+  - "{ echo '[defaults]'; echo 'roles_path = ../'; } >> ansible.cfg"
+
 
 script:
   # Check the roles syntax
   - "ansible-playbook -i tests/inventory tests/test.yml --syntax-check"
+
+  # Run the role
   - "ansible-playbook -i tests/inventory tests/test.yml --connection=local --sudo"
 
-
+  # Run the role/playbook again, checking to make sure it's idempotent.
+  - >
+    ansible-playbook -i tests/inventory tests/$SITE --connection=local --sudo
+    | grep -q 'changed=0.*failed=0'
+    && (echo 'Idempotence test: pass' && exit 0)
+    || (echo 'Idempotence test: fail' && exit 1)