diff --git a/src/shrpx_downstream.h b/src/shrpx_downstream.h
index 5bd0b225..7bde43d2 100644
--- a/src/shrpx_downstream.h
+++ b/src/shrpx_downstream.h
@@ -148,6 +148,7 @@ struct Request {
         method(-1),
         http_major(1),
         http_minor(1),
+        connect_proto(CONNECT_PROTO_NONE),
         upgrade_request(false),
         http2_upgrade_seen(false),
         connection_close(false),