diff --git a/src/HttpServer.cc b/src/HttpServer.cc
index a3770e07..9c076f2c 100644
--- a/src/HttpServer.cc
+++ b/src/HttpServer.cc
@@ -1354,7 +1354,7 @@ void prepare_response(Stream *stream, Http2Handler *hd,
   }
 
   auto method = stream->header.method;
-  if (method == "HEAD") {
+  if (method == StringRef::from_lit("HEAD")) {
     hd->submit_file_response(StringRef::from_lit("200"), stream,
                              file_ent->mtime, file_ent->length,
                              file_ent->content_type, nullptr);
@@ -1512,7 +1512,8 @@ int hd_on_frame_recv_callback(nghttp2_session *session,
 
       auto method = stream->header.method;
       if (hd->get_config()->echo_upload &&
-          (method == "POST" || method == "PUT")) {
+          (method == StringRef::from_lit("POST") ||
+           method == StringRef::from_lit("PUT"))) {
         if (!prepare_upload_temp_store(stream, hd)) {
           hd->submit_rst_stream(stream, NGHTTP2_INTERNAL_ERROR);
           return 0;
diff --git a/src/shrpx.cc b/src/shrpx.cc
index 8da4fafe..a4434707 100644
--- a/src/shrpx.cc
+++ b/src/shrpx.cc
@@ -524,7 +524,8 @@ int create_tcp_server_socket(UpstreamAddr &faddr,
   hints.ai_flags |= AI_ADDRCONFIG;
 #endif // AI_ADDRCONFIG
 
-  auto node = faddr.host == "*" ? nullptr : faddr.host.c_str();
+  auto node =
+      faddr.host == StringRef::from_lit("*") ? nullptr : faddr.host.c_str();
 
   addrinfo *res, *rp;
   rv = getaddrinfo(node, service.c_str(), &hints, &res);
@@ -720,7 +721,7 @@ int create_acceptor_socket() {
     auto type = StringRef(env, end_type);
     auto value = end_type + 1;
 
-    if (type == "unix") {
+    if (type == StringRef::from_lit("unix")) {
       auto endfd = strchr(value, ',');
       if (!endfd) {
         continue;
@@ -752,7 +753,7 @@ int create_acceptor_socket() {
       iaddrs.push_back(std::move(addr));
     }
 
-    if (type == "tcp") {
+    if (type == StringRef::from_lit("tcp")) {
       auto fd = util::parse_uint(value);
       if (fd == -1) {
         LOG(WARN) << "Could not parse file descriptor from " << value;
@@ -2132,7 +2133,7 @@ void process_options(int argc, char **argv,
   ssize_t catch_all_group = -1;
   for (size_t i = 0; i < addr_groups.size(); ++i) {
     auto &g = addr_groups[i];
-    if (g.pattern == "/") {
+    if (g.pattern == StringRef::from_lit("/")) {
       catch_all_group = i;
     }
     if (LOG_ENABLED(INFO)) {
diff --git a/src/shrpx_config.cc b/src/shrpx_config.cc
index 2ca55127..c259a137 100644
--- a/src/shrpx_config.cc
+++ b/src/shrpx_config.cc
@@ -831,7 +831,7 @@ int parse_error_page(std::vector<ErrorPage> &error_pages, const StringRef &opt,
   auto codestr = StringRef{std::begin(optarg), eq};
   unsigned int code;
 
-  if (codestr == "*") {
+  if (codestr == StringRef::from_lit("*")) {
     code = 0;
   } else {
     auto n = util::parse_uint(codestr);
diff --git a/src/shrpx_http2_upstream.cc b/src/shrpx_http2_upstream.cc
index 12788227..dc258b94 100644
--- a/src/shrpx_http2_upstream.cc
+++ b/src/shrpx_http2_upstream.cc
@@ -325,7 +325,8 @@ int Http2Upstream::on_request_headers(Downstream *downstream,
   }
 
   if (path) {
-    if (method_token == HTTP_OPTIONS && path->value == "*") {
+    if (method_token == HTTP_OPTIONS &&
+        path->value == StringRef::from_lit("*")) {
       // Server-wide OPTIONS request.  Path is empty.
     } else if (get_config()->http2_proxy) {
       req.path = path->value;
diff --git a/src/shrpx_https_upstream.cc b/src/shrpx_https_upstream.cc
index f2236731..2501c116 100644
--- a/src/shrpx_https_upstream.cc
+++ b/src/shrpx_https_upstream.cc
@@ -354,7 +354,7 @@ int htp_hdrs_completecb(http_parser *htp) {
 
       req.no_authority = true;
 
-      if (method == HTTP_OPTIONS && req.path == "*") {
+      if (method == HTTP_OPTIONS && req.path == StringRef::from_lit("*")) {
         req.path = StringRef{};
       } else {
         req.path = http2::rewrite_clean_path(balloc, req.path);
diff --git a/src/shrpx_spdy_upstream.cc b/src/shrpx_spdy_upstream.cc
index a3d002b5..040b5f6e 100644
--- a/src/shrpx_spdy_upstream.cc
+++ b/src/shrpx_spdy_upstream.cc
@@ -272,7 +272,8 @@ void on_ctrl_recv_callback(spdylay_session *session, spdylay_frame_type type,
       req.authority = host->value;
       if (get_config()->http2_proxy) {
         req.path = path->value;
-      } else if (method_token == HTTP_OPTIONS && path->value == "*") {
+      } else if (method_token == HTTP_OPTIONS &&
+                 path->value == StringRef::from_lit("*")) {
         // Server-wide OPTIONS request.  Path is empty.
       } else {
         req.path = http2::rewrite_clean_path(balloc, path->value);