diff --git a/src/shrpx_downstream.cc b/src/shrpx_downstream.cc
index 100cd965..2538aa95 100644
--- a/src/shrpx_downstream.cc
+++ b/src/shrpx_downstream.cc
@@ -764,19 +764,11 @@ bool Downstream::validate_response_recv_body_length() const {
 }
 
 void Downstream::check_upgrade_fulfilled_http2() {
-  if (req_.method == HTTP_CONNECT) {
-    // This handles nonzero req_.connect_proto as well.
-    upgraded_ = 200 <= resp_.http_status && resp_.http_status < 300;
-
-    return;
-  }
-
-  if (req_.connect_proto == CONNECT_PROTO_WEBSOCKET) {
-    // h1 frontend requests WebSocket upgrade
-    upgraded_ = resp_.http_status == 200;
-
-    return;
-  }
+  // This handles nonzero req_.connect_proto and h1 frontend requests
+  // WebSocket upgrade.
+  upgraded_ = (req_.method == HTTP_CONNECT ||
+               req_.connect_proto == CONNECT_PROTO_WEBSOCKET) &&
+              resp_.http_status / 100 == 2;
 }
 
 void Downstream::check_upgrade_fulfilled_http1() {
@@ -798,7 +790,7 @@ void Downstream::check_upgrade_fulfilled_http1() {
 
       upgraded_ = expected != "" && expected == accept->value;
     } else {
-      upgraded_ = 200 <= resp_.http_status && resp_.http_status < 300;
+      upgraded_ = resp_.http_status / 100 == 2;
     }
 
     return;
diff --git a/src/shrpx_http2_session.cc b/src/shrpx_http2_session.cc
index b48a93c6..5342a14c 100644
--- a/src/shrpx_http2_session.cc
+++ b/src/shrpx_http2_session.cc
@@ -620,7 +620,7 @@ int htp_hdrs_completecb(http_parser *htp) {
   http_parser_pause(htp, 1);
 
   // We just check status code here
-  if (htp->status_code == 200) {
+  if (htp->status_code / 100 == 2) {
     if (LOG_ENABLED(INFO)) {
       SSLOG(INFO, http2session) << "Tunneling success";
     }
diff --git a/src/shrpx_http_downstream_connection.cc b/src/shrpx_http_downstream_connection.cc
index b93c8e80..31f48a24 100644
--- a/src/shrpx_http_downstream_connection.cc
+++ b/src/shrpx_http_downstream_connection.cc
@@ -938,7 +938,7 @@ int htp_hdrs_completecb(http_parser *htp) {
 
   // Server MUST NOT send Transfer-Encoding with a status code 1xx or
   // 204.  Also server MUST NOT send Transfer-Encoding with a status
-  // code 200 to a CONNECT request.  Same holds true with
+  // code 2xx to a CONNECT request.  Same holds true with
   // Content-Length.
   if (resp.http_status == 204) {
     if (resp.fs.header(http2::HD_TRANSFER_ENCODING)) {
@@ -960,7 +960,7 @@ int htp_hdrs_completecb(http_parser *htp) {
       return -1;
     }
   } else if (resp.http_status / 100 == 1 ||
-             (resp.http_status == 200 && req.method == HTTP_CONNECT)) {
+             (resp.http_status / 100 == 2 && req.method == HTTP_CONNECT)) {
     if (resp.fs.header(http2::HD_CONTENT_LENGTH) ||
         resp.fs.header(http2::HD_TRANSFER_ENCODING)) {
       return -1;
diff --git a/src/shrpx_https_upstream.cc b/src/shrpx_https_upstream.cc
index ce800cc8..b6953a76 100644
--- a/src/shrpx_https_upstream.cc
+++ b/src/shrpx_https_upstream.cc
@@ -1147,7 +1147,7 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
 
   if (!connect_method && downstream->get_upgraded()) {
     if (req.connect_proto == CONNECT_PROTO_WEBSOCKET &&
-        resp.http_status == 200) {
+        resp.http_status / 100 == 2) {
       buf->append("Upgrade: websocket\r\nConnection: Upgrade\r\n");
       auto key = req.fs.header(http2::HD_SEC_WEBSOCKET_KEY);
       if (!key || key->value.size() != base64::encode_length(16)) {