diff --git a/src/http2.cc b/src/http2.cc
index 31423ed3..8bb09c7f 100644
--- a/src/http2.cc
+++ b/src/http2.cc
@@ -69,12 +69,16 @@ std::string get_status_string(unsigned int status_code)
   case 416: return "416 Requested Range Not Satisfiable";
   case 417: return "417 Expectation Failed";
   case 426: return "426 Upgrade Required";
+  case 428: return "428 Precondition Required";
+  case 429: return "429 Too Many Requests";
+  case 431: return "431 Request Header Fields Too Large";
   case 500: return "500 Internal Server Error";
   case 501: return "501 Not Implemented";
   case 502: return "502 Bad Gateway";
   case 503: return "503 Service Unavailable";
   case 504: return "504 Gateway Timeout";
   case 505: return "505 HTTP Version Not Supported";
+  case 511: return "511 Network Authentication Required";
   default: return util::utos(status_code);
   }
 }