diff --git a/lib/vquic/curl_ngtcp2.c b/lib/vquic/curl_ngtcp2.c
index f397ec85ae..9851a087c1 100644
--- a/lib/vquic/curl_ngtcp2.c
+++ b/lib/vquic/curl_ngtcp2.c
@@ -2744,8 +2744,9 @@ static bool cf_ngtcp2_conn_is_alive(struct Curl_cfilter *cf,
    * it will close the connection when it expires. */
   rp = ngtcp2_conn_get_remote_transport_params(ctx->qconn);
   if(rp && rp->max_idle_timeout) {
-    timediff_t idletime = curlx_timediff(curlx_now(), ctx->q.last_io);
-    if(idletime > 0 && (uint64_t)idletime > rp->max_idle_timeout)
+    timediff_t idletime_ms = curlx_timediff(curlx_now(), ctx->q.last_io);
+    if(idletime_ms > 0 &&
+      ((uint64_t)idletime_ms * NGTCP2_MILLISECONDS) > rp->max_idle_timeout)
       goto out;
   }
 
diff --git a/lib/vquic/curl_osslq.c b/lib/vquic/curl_osslq.c
index cda239a57d..474ed595cb 100644
--- a/lib/vquic/curl_osslq.c
+++ b/lib/vquic/curl_osslq.c
@@ -2251,10 +2251,11 @@ static bool cf_osslq_conn_is_alive(struct Curl_cfilter *cf,
                   "assume connection is dead.");
       goto out;
     }
-    CURL_TRC_CF(data, cf, "negotiated idle timeout: %zums", (size_t)idle_ms);
+    CURL_TRC_CF(data, cf, "negotiated idle timeout: %" FMT_PRIu64 "ms",
+                (curl_uint64_t)idle_ms);
     idletime = curlx_timediff(curlx_now(), ctx->q.last_io);
-    if(idletime > 0 && (uint64_t)idletime > idle_ms)
-      goto out;
+    if(idle_ms != 0 && idletime > 0 && (uint64_t)idletime > idle_ms)
+       goto out;
   }
 
 #endif