diff --git a/src/shrpx.cc b/src/shrpx.cc
index 2ff9f241..b06938d8 100644
--- a/src/shrpx.cc
+++ b/src/shrpx.cc
@@ -318,6 +318,14 @@ bool conf_exists(const char *path)
 }
 } // namespace
 
+namespace {
+const char *DEFAULT_NPN_LIST = NGHTTP2_PROTO_VERSION_ID ","
+#ifdef HAVE_SPDYLAY
+  "spdy/3,spdy/2,"
+#endif // HAVE_SPDYLAY
+  "http/1.1";
+} // namespace
+
 namespace {
 void fill_default_config()
 {
@@ -405,6 +413,7 @@ void fill_default_config()
   mod_config()->read_burst = 4*1024*1024;
   mod_config()->write_rate = 0;
   mod_config()->write_burst = 0;
+  mod_config()->npn_list = nullptr;
 }
 } // namespace
 
@@ -573,7 +582,14 @@ void print_help(std::ostream& out)
       << "    --dh-param-file=<PATH>\n"
       << "                       Path to file that contains DH parameters in\n"
       << "                       PEM format. Without this option, DHE cipher\n"
-      << "                       suites are not available."
+      << "                       suites are not available.\n"
+      << "    --npn-list=<LIST>  Comma delimited list of NPN protocol sorted\n"
+      << "                       in the order of preference. That means\n"
+      << "                       most desirable protocol comes first.\n"
+      << "                       The parameter must be delimited by a single\n"
+      << "                       comma only and any white spaces are treated\n"
+      << "                       as a part of protocol string.\n"
+      << "                       Default: " << DEFAULT_NPN_LIST << "\n"
       << "\n"
       << "  HTTP/2.0 and SPDY:\n"
       << "    -c, --spdy-max-concurrent-streams=<NUM>\n"
@@ -710,6 +726,7 @@ int main(int argc, char **argv)
       {"read-burst", required_argument, &flag, 35},
       {"write-rate", required_argument, &flag, 36},
       {"write-burst", required_argument, &flag, 37},
+      {"npn-list", required_argument, &flag, 38},
       {nullptr, 0, nullptr, 0 }
     };
     int option_index = 0;
@@ -909,6 +926,10 @@ int main(int argc, char **argv)
         // --write-burst
         cmdcfgs.push_back(std::make_pair(SHRPX_OPT_WRITE_BURST, optarg));
         break;
+      case 38:
+        // --npn-list
+        cmdcfgs.push_back(std::make_pair(SHRPX_OPT_NPN_LIST, optarg));
+        break;
       default:
         break;
       }
@@ -947,6 +968,10 @@ int main(int argc, char **argv)
     }
   }
 
+  if(!get_config()->npn_list) {
+    parse_config_npn_list(DEFAULT_NPN_LIST);
+  }
+
   if(get_config()->cert_file && get_config()->private_key_file) {
     mod_config()->default_ssl_ctx =
       ssl::create_ssl_context(get_config()->private_key_file,
diff --git a/src/shrpx_config.cc b/src/shrpx_config.cc
index 1f2d36df..a4560d6b 100644
--- a/src/shrpx_config.cc
+++ b/src/shrpx_config.cc
@@ -99,6 +99,7 @@ const char SHRPX_OPT_READ_RATE[] = "read-rate";
 const char SHRPX_OPT_READ_BURST[] = "read-burst";
 const char SHRPX_OPT_WRITE_RATE[] = "write-rate";
 const char SHRPX_OPT_WRITE_BURST[] = "write-burst";
+const char SHRPX_OPT_NPN_LIST[] = "npn-list";
 
 namespace {
 Config *config = 0;
@@ -194,6 +195,31 @@ void set_config_str(char **destp, const char *val)
   *destp = strdup(val);
 }
 
+int parse_config_npn_list(const char *s)
+{
+  delete [] mod_config()->npn_list;
+  size_t len = 1;
+  for(const char *first = s, *p = nullptr; (p = strchr(first, ','));
+      ++len, first = p + 1);
+  auto list = new char*[len];
+  auto t = strdup(s);
+  auto first = t;
+  len = 0;
+  for(;;) {
+    auto p = strchr(first, ',');
+    if(p == nullptr) {
+      break;
+    }
+    list[len++] = first;
+    *p = '\0';
+    first = p + 1;
+  }
+  list[len++] = first;
+  mod_config()->npn_list = list;
+  mod_config()->npn_list_len = len;
+  return 0;
+}
+
 int parse_config(const char *opt, const char *optarg)
 {
   char host[NI_MAXHOST];
@@ -385,6 +411,8 @@ int parse_config(const char *opt, const char *optarg)
     mod_config()->write_rate = strtoul(optarg, nullptr, 10);
   } else if(util::strieq(opt, SHRPX_OPT_WRITE_BURST)) {
     mod_config()->write_burst = strtoul(optarg, nullptr, 10);
+  } else if(util::strieq(opt, SHRPX_OPT_NPN_LIST)) {
+    parse_config_npn_list(optarg);
   } else if(util::strieq(opt, "conf")) {
     LOG(WARNING) << "conf is ignored";
   } else {
diff --git a/src/shrpx_config.h b/src/shrpx_config.h
index 141d169f..91e323da 100644
--- a/src/shrpx_config.h
+++ b/src/shrpx_config.h
@@ -90,6 +90,7 @@ extern const char SHRPX_OPT_READ_RATE[];
 extern const char SHRPX_OPT_READ_BURST[];
 extern const char SHRPX_OPT_WRITE_RATE[];
 extern const char SHRPX_OPT_WRITE_BURST[];
+extern const char SHRPX_OPT_NPN_LIST[];
 
 union sockaddr_union {
   sockaddr sa;
@@ -178,6 +179,11 @@ struct Config {
   size_t read_burst;
   size_t write_rate;
   size_t write_burst;
+  // Comma delimited list of NPN protocol strings in the order of
+  // preference.
+  char **npn_list;
+  // The number of elements in npn_list
+  size_t npn_list_len;
 };
 
 const Config* get_config();
@@ -197,6 +203,14 @@ int load_config(const char *filename);
 // Read passwd from |filename|
 std::string read_passwd_from_file(const char *filename);
 
+// Parses NPN protocol strings in |s| and stores the protocols list in
+// mod_config()->npn_list and assigns the number of elements in
+// mod_config()->npn_list_len. The |s| must be comma delimited list of
+// protocol strings. The strings must be delimited by a single command
+// and any white spaces around it are treated as a part of protocol
+// strings.  This function always succeeds and returns 0.
+int parse_config_npn_list(const char *s);
+
 // Copies NULL-terminated string |val| to |*destp|. If |*destp| is not
 // NULL, it is freed before copying.
 void set_config_str(char **destp, const char *val);
diff --git a/src/shrpx_ssl.cc b/src/shrpx_ssl.cc
index 15bbbf46..2aac7677 100644
--- a/src/shrpx_ssl.cc
+++ b/src/shrpx_ssl.cc
@@ -80,7 +80,7 @@ int verify_callback(int preverify_ok, X509_STORE_CTX *ctx)
 } // namespace
 
 namespace {
-size_t set_npn_prefs(unsigned char *out, const char **protos, size_t len)
+size_t set_npn_prefs(unsigned char *out, char **protos, size_t len)
 {
   unsigned char *ptr = out;
   size_t listlen = 0;
@@ -220,14 +220,8 @@ SSL_CTX* create_ssl_context(const char *private_key_file,
   }
   SSL_CTX_set_tlsext_servername_callback(ssl_ctx, servername_callback);
 
-
-  const char *protos[] = { NGHTTP2_PROTO_VERSION_ID,
-#ifdef HAVE_SPDYLAY
-                           "spdy/3", "spdy/2",
-#endif // HAVE_SPDYLAY
-                           "http/1.1" };
-  auto proto_list_len = set_npn_prefs(proto_list, protos,
-                                      sizeof(protos)/sizeof(protos[0]));
+  auto proto_list_len = set_npn_prefs(proto_list, get_config()->npn_list,
+                                      get_config()->npn_list_len);
   next_proto.first = proto_list;
   next_proto.second = proto_list_len;
   SSL_CTX_set_next_protos_advertised_cb(ssl_ctx, next_proto_cb, &next_proto);