diff --git a/roles/repositories/tasks/debian-stable.yml b/roles/repositories/tasks/debian-stable.yml
--- a/roles/repositories/tasks/debian-stable.yml
+++ b/roles/repositories/tasks/debian-stable.yml
@@ -1,9 +1,17 @@
 ---
-- name: add backports repo
+- name: "add backports repo"
   apt_repository:
     repo: "deb http://http.debian.net/debian {{ansible_distribution_release}}-backports main"
+    update_cache: false
 
-- name: add pgdg repo
+- name: "add pgdg repo"
   apt_repository:
     repo: "deb http://apt.postgresql.org/pub/repos/apt/ {{ansible_distribution_release}}-pgdg main"
+    update_cache: false
   when: ansible_architecture in ["i386", "x86_64"]
+
+- name: "remove defunct repositories"
+  apt_repository:
+    state: absent
+    repo: "deb http://mozilla.debian.net/ {{ansible_distribution_release}}-backports firefox-release"
+    update_cache: false