diff --git a/roles/ensure-nodejs/README.rst b/roles/ensure-nodejs/README.rst
index 09f7e0679..eda190572 100644
--- a/roles/ensure-nodejs/README.rst
+++ b/roles/ensure-nodejs/README.rst
@@ -3,4 +3,5 @@ Install NodeJS from nodesource
 **Role Variables**
 
 .. zuul:rolevar:: node_version
-   :default: 6
+
+   Required. What version of Node to install.
diff --git a/roles/ensure-nodejs/tasks/main.yaml b/roles/ensure-nodejs/tasks/main.yaml
index c97152fc0..0437edc76 100644
--- a/roles/ensure-nodejs/tasks/main.yaml
+++ b/roles/ensure-nodejs/tasks/main.yaml
@@ -1,3 +1,7 @@
+- name: Ensure we know what version of node to install
+  assert:
+    that: node_version is defined
+
 - name: Update apt cache
   apt:
     update_cache: yes