diff --git a/lib/connect.c b/lib/connect.c
index 6c9464360..f9dd415ba 100644
--- a/lib/connect.c
+++ b/lib/connect.c
@@ -908,8 +908,10 @@ CURLcode Curl_is_connected(struct Curl_easy *data,
         connkeep(conn, "HTTP/3 default");
         return CURLE_OK;
       }
-      if(result)
+      if(result) {
+        conn->tempsock[i] = CURL_SOCKET_BAD;
         error = SOCKERRNO;
+      }
     }
     else
 #endif
diff --git a/lib/vquic/quiche.c b/lib/vquic/quiche.c
index 9b476cbd2..a3870749b 100644
--- a/lib/vquic/quiche.c
+++ b/lib/vquic/quiche.c
@@ -360,6 +360,8 @@ static CURLcode process_ingress(struct Curl_easy *data, int sockfd,
   uint8_t *buf = (uint8_t *)data->state.buffer;
   size_t bufsize = data->set.buffer_size;
 
+  DEBUGASSERT(qs->conn);
+
   /* in case the timeout expired */
   quiche_conn_on_timeout(qs->conn);