diff --git a/README.md b/README.md
index 8296334..b61cb43 100644
--- a/README.md
+++ b/README.md
@@ -21,7 +21,8 @@ Write this to `DIGITALOCEAN_TOKEN`.
 The script should now run. Try it out:
 
 ```sh
-./dyndns.sh
+./dyndns.sh 4 # for IPv$
+./dyndns.sh 6 # for IPv$
 ```
 
 Go to the control panel in DigitalOcean for your domain, and check the A and
@@ -40,3 +41,10 @@ Wait one minute, and check the logs. If you want to see that it works, delete
 the REPEAT_CHECK_A and REPEAT_CHECK_AAAA files and wait for the script to run
 again. You may also want to have an MTA set up, as cron will try to send any
 unhandled output to your inbox.
+
+If you want to use this script for more than one domain, you can supply a domain
+name as a second argument. For example:
+
+```sh
+./dyndns.sh 4 example.com
+```
diff --git a/dyndns.sh b/dyndns.sh
index 005264b..4b7d1ca 100755
--- a/dyndns.sh
+++ b/dyndns.sh
@@ -7,7 +7,7 @@
 ip_version="$1"
 if [ -z "${ip_version:-}" ] || ([ "$ip_version" != 4 ] && [ "$ip_version" != 6 ]); then
     echo "Error: no valid IP version provided" >&2
-    echo "Usage: dyndns.bash <4|6>" >&2
+    echo "Usage: dyndns.bash <4|6> [domain]" >&2
     exit 1
 fi
 
@@ -26,7 +26,7 @@ REPEAT_CHECK_A=$REPEAT_CHECK_DIR/REPEAT_CHECK_A
 REPEAT_CHECK_AAAA=$REPEAT_CHECK_DIR/REPEAT_CHECK_AAAA
 REPEAT_CHECK="$([ $ip_version = 4 ] && echo $REPEAT_CHECK_A || echo $REPEAT_CHECK_AAAA)"
 
-DIGITALOCEAN_DOMAIN=`cat $SCRIPT_DIR/DIGITALOCEAN_DOMAIN`
+DIGITALOCEAN_DOMAIN=${2:-`cat $SCRIPT_DIR/DIGITALOCEAN_DOMAIN`}
 DIGITALOCEAN_TOKEN=`cat $SCRIPT_DIR/DIGITALOCEAN_TOKEN`
 
 get_a_record_ids() {