diff --git a/src/app_helper.cc b/src/app_helper.cc
index 77fa5c24..107423b0 100644
--- a/src/app_helper.cc
+++ b/src/app_helper.cc
@@ -77,6 +77,8 @@ const char *strsettingsid(int32_t id) {
     return "SETTINGS_MAX_FRAME_SIZE";
   case NGHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE:
     return "SETTINGS_MAX_HEADER_LIST_SIZE";
+  case NGHTTP2_SETTINGS_ENABLE_CONNECT_PROTOCOL:
+    return "SETTINGS_ENABLE_CONNECT_PROTOCOL";
   default:
     return "UNKNOWN";
   }