diff --git a/roles/configure-mirrors/templates/apt/etc/apt/sources.list.j2 b/roles/configure-mirrors/templates/apt/etc/apt/sources.list.j2
index 2d6444aaa..de4073d58 100644
--- a/roles/configure-mirrors/templates/apt/etc/apt/sources.list.j2
+++ b/roles/configure-mirrors/templates/apt/etc/apt/sources.list.j2
@@ -1,3 +1,4 @@
+#jinja2: trim_blocks:False
 # {{ ansible_managed }}
 deb {% if set_apt_mirrors_trusted %}[ trusted=yes ] {% endif %}{{ package_mirror }} {{ ansible_distribution_release }} main universe
 deb {% if set_apt_mirrors_trusted %}[ trusted=yes ] {% endif %}{{ package_mirror }} {{ ansible_distribution_release }}-updates main universe
diff --git a/test-playbooks/base-roles/configure-mirrors.yaml b/test-playbooks/base-roles/configure-mirrors.yaml
index 114ad5a2d..cd26a9562 100644
--- a/test-playbooks/base-roles/configure-mirrors.yaml
+++ b/test-playbooks/base-roles/configure-mirrors.yaml
@@ -37,3 +37,19 @@
         name: "{{ emacs_package | default('emacs') }}"
         state: "present"
       become: yes
+
+- name: Ensure no apt warnings
+  hosts: all
+  tasks:
+    - name: Check apt output
+      when: ansible_distribution == 'Debian' or ansible_distribution == 'Ubuntu'
+      block:
+        - name: Run apt-get update
+          command: 'apt-get update'
+          register: _apt_get_output
+          become: yes
+
+        - name: Check for warnings in output
+          fail:
+            msg: 'Warnings found in apt output'
+          when: _apt_get_output is regex('^W:.*$')