diff --git a/lib/vquic/ngtcp2.c b/lib/vquic/ngtcp2.c
index 15184827ab..7f076759b8 100644
--- a/lib/vquic/ngtcp2.c
+++ b/lib/vquic/ngtcp2.c
@@ -934,6 +934,7 @@ static const struct Curl_handler Curl_handler_http3 = {
   ng_disconnect,                        /* disconnect */
   ZERO_NULL,                            /* readwrite */
   ng_conncheck,                         /* connection_check */
+  ZERO_NULL,                            /* attach connection */
   PORT_HTTP,                            /* defport */
   CURLPROTO_HTTPS,                      /* protocol */
   CURLPROTO_HTTP,                       /* family */
diff --git a/lib/vquic/quiche.c b/lib/vquic/quiche.c
index 33d303d443..d0d04780ed 100644
--- a/lib/vquic/quiche.c
+++ b/lib/vquic/quiche.c
@@ -157,6 +157,7 @@ static const struct Curl_handler Curl_handler_http3 = {
   quiche_disconnect,                    /* disconnect */
   ZERO_NULL,                            /* readwrite */
   quiche_conncheck,                     /* connection_check */
+  ZERO_NULL,                            /* attach connection */
   PORT_HTTP,                            /* defport */
   CURLPROTO_HTTPS,                      /* protocol */
   CURLPROTO_HTTP,                       /* family */