diff --git a/README.md b/README.md
index a420e8c..5af404f 100644
--- a/README.md
+++ b/README.md
@@ -29,8 +29,9 @@ Whether to restart the Docker daemon after the Docker package is installed or up
 
 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 }}"
     docker_apt_ignore_key_error: True
 
 (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 3448d79..d54fb72 100644
--- a/defaults/main.yml
+++ b/defaults/main.yml
@@ -12,7 +12,9 @@ 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 }}"
 docker_apt_ignore_key_error: True
 
 # Used only for RedHat/CentOS/Fedora.