diff --git a/README.md b/README.md
index c1d34cb..1a227f1 100644
--- a/README.md
+++ b/README.md
@@ -48,9 +48,16 @@ $ http --json ifconfig.co
 }
 ```
 
+Pass the appropriate flag (usually `-4` and `-6`) to your tool to switch between
+IPv4 and IPv6 lookup.
+
+The subdomains https://v4.ifconfig.co and https://v6.ifconfig.co can be used to
+force IPv4 or IPv6 lookup.
+
 ## Features
 
 * Easy to remember domain name
+* Supports IPv4 and IPv6
 * Supports HTTPS
 * Open source under the [BSD 3-Clause license](https://opensource.org/licenses/BSD-3-Clause)
 * Fast
@@ -62,7 +69,7 @@ $ http --json ifconfig.co
 
 * To scratch an itch
 * An excuse to use Go for something
-* Faster than ifconfig.me
+* Faster than ifconfig.me and has IPv6 support
 
 ## Building
 
diff --git a/index.html b/index.html
index b70c7f0..e606050 100644
--- a/index.html
+++ b/index.html
@@ -102,6 +102,8 @@ $ http {{ .Host }}/port/8080
       </div>
       <div class="pure-u-1 pure-u-md-1-1">
         <h2>FAQ</h2>
+        <h3>How do I force IPv4 or IPv6 lookup?</h3>
+        <p>IPv4 or IPv6 lookup can be forced by using the <a href="//v4.ifconfig.co">v4</a> and <a href="//v6.ifconfig.co">v6<a> subdomains.</p>
 
         <h3>Is using this service from automated scripts/tools permitted?</h3>
         <p>Yes, as long as the rate limit is respected. <em>Please limit