diff --git a/src/h2load.cc b/src/h2load.cc
index 665bc4d1..0cbcaebb 100644
--- a/src/h2load.cc
+++ b/src/h2load.cc
@@ -2033,7 +2033,7 @@ Options:
               Default: 1
   -w, --window-bits=<N>
               Sets the stream level initial window size to (2**<N>)-1.
-              For QUIC, <N> is capped to 23 (roughly 8MiB).
+              For QUIC, <N> is capped to 26 (roughly 64MiB).
               Default: )"
       << config.window_bits << R"(
   -W, --connection-window-bits=<N>
diff --git a/src/h2load_quic.cc b/src/h2load_quic.cc
index b08ffd49..720b7038 100644
--- a/src/h2load_quic.cc
+++ b/src/h2load_quic.cc
@@ -367,7 +367,7 @@ int Client::quic_init(const sockaddr *local_addr, socklen_t local_addrlen,
   settings.initial_ts = timestamp(worker->loop);
   auto &params = settings.transport_params;
   auto max_stream_data =
-      std::min((1 << 23) - 1, (1 << config->window_bits) - 1);
+      std::min((1 << 26) - 1, (1 << config->window_bits) - 1);
   params.initial_max_stream_data_bidi_local = max_stream_data;
   params.initial_max_stream_data_uni = max_stream_data;
   params.initial_max_data = (1 << config->connection_window_bits) - 1;