diff --git a/src/shrpx_http2_upstream.cc b/src/shrpx_http2_upstream.cc
index 0772b8dc..83af04fa 100644
--- a/src/shrpx_http2_upstream.cc
+++ b/src/shrpx_http2_upstream.cc
@@ -306,8 +306,11 @@ int Http2Upstream::on_request_headers(Downstream *downstream,
     return 0;
   }
 
-  // For HTTP/2 proxy, we request :authority.
-  if (method_token != HTTP_CONNECT && get_config()->http2_proxy && !authority) {
+  auto faddr = handler_->get_upstream_addr();
+
+  // For HTTP/2 proxy, we require :authority.
+  if (method_token != HTTP_CONNECT && get_config()->http2_proxy &&
+      !faddr->alt_mode && !authority) {
     rst_stream(downstream, NGHTTP2_PROTOCOL_ERROR);
     return 0;
   }
@@ -331,7 +334,7 @@ int Http2Upstream::on_request_headers(Downstream *downstream,
     if (method_token == HTTP_OPTIONS &&
         path->value == StringRef::from_lit("*")) {
       // Server-wide OPTIONS request.  Path is empty.
-    } else if (get_config()->http2_proxy) {
+    } else if (get_config()->http2_proxy && !faddr->alt_mode) {
       req.path = path->value;
     } else {
       req.path = http2::rewrite_clean_path(downstream->get_block_allocator(),
diff --git a/src/shrpx_https_upstream.cc b/src/shrpx_https_upstream.cc
index 50b5b16a..2bfaaf13 100644
--- a/src/shrpx_https_upstream.cc
+++ b/src/shrpx_https_upstream.cc
@@ -202,7 +202,7 @@ int htp_hdr_valcb(http_parser *htp, const char *data, size_t len) {
 namespace {
 void rewrite_request_host_path_from_uri(BlockAllocator &balloc, Request &req,
                                         const StringRef &uri,
-                                        http_parser_url &u) {
+                                        http_parser_url &u, bool http2_proxy) {
   assert(u.field_set & (1 << UF_HOST));
 
   // As per https://tools.ietf.org/html/rfc7230#section-5.4, we
@@ -271,7 +271,7 @@ void rewrite_request_host_path_from_uri(BlockAllocator &balloc, Request &req,
     }
   }
 
-  if (get_config()->http2_proxy) {
+  if (http2_proxy) {
     req.path = path;
   } else {
     req.path = http2::rewrite_clean_path(balloc, path);
@@ -338,6 +338,7 @@ int htp_hdrs_completecb(http_parser *htp) {
 
   downstream->inspect_http1_request();
 
+  auto faddr = handler->get_upstream_addr();
   auto &balloc = downstream->get_block_allocator();
 
   if (method != HTTP_CONNECT) {
@@ -349,7 +350,7 @@ int htp_hdrs_completecb(http_parser *htp) {
     }
     // checking UF_HOST could be redundant, but just in case ...
     if (!(u.field_set & (1 << UF_SCHEMA)) || !(u.field_set & (1 << UF_HOST))) {
-      if (get_config()->http2_proxy) {
+      if (get_config()->http2_proxy && !faddr->alt_mode) {
         // Request URI should be absolute-form for client proxy mode
         return -1;
       }
@@ -372,7 +373,9 @@ int htp_hdrs_completecb(http_parser *htp) {
         req.scheme = StringRef::from_lit("http");
       }
     } else {
-      rewrite_request_host_path_from_uri(balloc, req, req.path, u);
+      rewrite_request_host_path_from_uri(balloc, req, req.path, u,
+                                         get_config()->http2_proxy &&
+                                             !faddr->alt_mode);
     }
   }
 
@@ -411,8 +414,6 @@ int htp_hdrs_completecb(http_parser *htp) {
     return -1;
   }
 
-  auto faddr = handler->get_upstream_addr();
-
   if (faddr->alt_mode) {
     // Normally, we forward expect: 100-continue to backend server,
     // and let them decide whether responds with 100 Continue or not.
diff --git a/src/shrpx_spdy_upstream.cc b/src/shrpx_spdy_upstream.cc
index ef68bb20..0bd86c4b 100644
--- a/src/shrpx_spdy_upstream.cc
+++ b/src/shrpx_spdy_upstream.cc
@@ -267,7 +267,11 @@ void on_ctrl_recv_callback(spdylay_session *session, spdylay_frame_type type,
     } else {
       req.scheme = scheme->value;
       req.authority = host->value;
-      if (get_config()->http2_proxy) {
+
+      auto handler = upstream->get_client_handler();
+      auto faddr = handler->get_upstream_addr();
+
+      if (get_config()->http2_proxy && !faddr->alt_mode) {
         req.path = path->value;
       } else if (method_token == HTTP_OPTIONS &&
                  path->value == StringRef::from_lit("*")) {