diff --git a/README.md b/README.md
index c7e81da..454be56 100644
--- a/README.md
+++ b/README.md
@@ -25,8 +25,9 @@ The `docker_edition` should be either `ce` (Community Edition) or `ee` (Enterpri
 
 Docker Compose installation options.
 
+    docker_apt_arch: amd64
     docker_apt_release_channel: stable
-    docker_apt_repository: "deb https://download.docker.com/linux/{{ ansible_distribution|lower }} {{ ansible_distribution_release }} {{ docker_apt_release_channel }}"
+    docker_apt_repository: "deb [arch={{ docker_apt_arch }}] https://download.docker.com/linux/{{ ansible_distribution|lower }} {{ ansible_distribution_release }} {{ docker_apt_release_channel }}"
 
 (Used only for Debian/Ubuntu.) You can switch the channel to `edge` if you want to use the Edge release.
 
diff --git a/defaults/main.yml b/defaults/main.yml
index 3573df1..1cb4d22 100644
--- a/defaults/main.yml
+++ b/defaults/main.yml
@@ -11,7 +11,9 @@ docker_compose_path: /usr/local/bin/docker-compose
 
 # Used only for Debian/Ubuntu. Switch 'stable' to 'edge' if needed.
 docker_apt_release_channel: stable
-docker_apt_repository: "deb https://download.docker.com/linux/{{ ansible_distribution|lower }} {{ ansible_distribution_release }} {{ docker_apt_release_channel }}"
+# Architecture must be specified in order for updates to work. Choose between 'amd64' & 'i386'.
+docker_apt_arch: amd64 
+docker_apt_repository: "deb [arch={{ docker_apt_arch }}] https://download.docker.com/linux/{{ ansible_distribution|lower }} {{ ansible_distribution_release }} {{ docker_apt_release_channel }}"
 
 # Used only for RedHat/CentOS.
 docker_yum_repo_url: https://download.docker.com/linux/centos/docker-{{ docker_edition }}.repo