diff --git a/.travis.yml b/.travis.yml
index 303f87c..cdb8a7a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,7 +4,7 @@ env:
   # CentOS 7.
   - container_id: $(mktemp)
     distribution: centos
-    version: 7
+    version: "7"
     init: /usr/lib/systemd/systemd
     run_opts: "--privileged --volume=/sys/fs/cgroup:/sys/fs/cgroup:ro"
   # Ubuntu 12.04.
@@ -28,11 +28,11 @@ before_install:
   # Pull container.
   - "sudo docker pull ${distribution}:${version}"
   # Customize container.
-  - "sudo docker build --rm=true --file=tests/Dockerfile.${distribution}-${version} --tag=${distribution}-${version}:ansible tests"
+  - "sudo docker build --rm=true --file=tests/Dockerfile.${distribution}${version} --tag=${distribution}${version}:ansible tests"
 
 script:
   # Run container in detached state.
-  - 'sudo docker run --detach --volume="${PWD}":/etc/ansible/roles/role_under_test:ro ${run_opts} ${distribution}-${version}:ansible "${init}" > "${container_id}"'
+  - 'sudo docker run --detach --volume="${PWD}":/etc/ansible/roles/role_under_test:ro ${run_opts} ${distribution}${version}:ansible "${init}" > "${container_id}"'
 
   # Ansible syntax check.
   - 'sudo docker exec --tty "$(cat ${container_id})" env TERM=xterm ansible-playbook /etc/ansible/roles/role_under_test/tests/test.yml --syntax-check'
diff --git a/tests/Dockerfile.ubuntu.12.04 b/tests/Dockerfile.ubuntu.12.04
deleted file mode 100644
index 1475a46..0000000
--- a/tests/Dockerfile.ubuntu.12.04
+++ /dev/null
@@ -1,10 +0,0 @@
-FROM ubuntu:14.04
-
-# Install Ansible
-RUN apt-get install -y software-properties-common git
-RUN apt-add-repository -y ppa:ansible/ansible
-RUN apt-get update
-RUN apt-get install -y ansible
-
-# Install Ansible inventory file
-RUN echo "[local]\nlocalhost ansible_connection=local" > /etc/ansible/hosts