diff --git a/ddclient.in b/ddclient.in
index 22580bb..7fa4c22 100755
--- a/ddclient.in
+++ b/ddclient.in
@@ -6445,7 +6445,11 @@ sub nic_duckdns_update {
         $url .= $h;
         $url .= "&token=";
         $url .= $config{$h}{'password'};
-        $url .= "&ip=";
+        if (is_ipv6($ip)) {
+            $url .= "&ipv6=";
+        } else {
+            $url .= "&ip=";
+        }
         $url .= $ip;