diff --git a/README.md b/README.md
index bc30e28..8fd7528 100644
--- a/README.md
+++ b/README.md
@@ -45,6 +45,8 @@ You can set Shepherd to roll back a service to the previous version if the updat
 
 You can control additional parameters for the `docker service update` and `docker service update --rollback` calls using the variables `UPDATE_OPTIONS` and `ROLLBACK_OPTIONS`.
 
+If the `docker service update` takes too long then it will be killed after 5 minutes by default. You can adjust this value using the `TIMEOUT` variable.
+
 You can enable private registry authentication by setting the `WITH_REGISTRY_AUTH` variable.
 
 If you need to authenticate to a registry (for example in order to get around the [Docker Hub rate limits](https://www.docker.com/increase-rate-limit)), you can set the variable `REGISTRY_USER` and store the password either in a [docker secret](https://docs.docker.com/engine/swarm/secrets/) named `shepherd_registry_password` or in the environment variable `REGISTRY_PASSWORD`. If you are not using Docker Hub but a private registry, set `REGISTRY_HOST` to the hostname of your registry.
diff --git a/shepherd b/shepherd
index ee3a2a9..b8c1578 100755
--- a/shepherd
+++ b/shepherd
@@ -98,7 +98,7 @@ update_services() {
       logger "Trying to update service $name with image $image" "true"
 
       # shellcheck disable=SC2086
-      if ! docker "${config_flag[@]}" service update "$name" $detach_option $registry_auth $no_resolve_image_flag ${UPDATE_OPTIONS} --image="$image" > /dev/null; then
+      if ! timeout "${TIMEOUT:-300}" docker "${config_flag[@]}" service update "$name" $detach_option $registry_auth $no_resolve_image_flag ${UPDATE_OPTIONS} --image="$image" > /dev/null; then
         logger "Service $name update failed on $hostname!"
         if [[ "${ROLLBACK_ON_FAILURE+x}" ]]; then
           logger "Rolling $name back"