diff --git a/src/brpc/policy/http2_rpc_protocol.cpp b/src/brpc/policy/http2_rpc_protocol.cpp
index 5b0538d332..f9b01206a0 100644
--- a/src/brpc/policy/http2_rpc_protocol.cpp
+++ b/src/brpc/policy/http2_rpc_protocol.cpp
@@ -744,7 +744,7 @@ H2ParseResult H2StreamContext::OnData(
 
     const int64_t acc = _deferred_window_update.fetch_add(frag_size, butil::memory_order_relaxed) + frag_size;
     // Allocate the quota of the window to each stream.
-    if (acc >= _conn_ctx->local_settings().stream_window_size / (_conn_ctx->VolatilePendingStreamSize() + 1)) {
+    if (acc >= static_cast<int64_t>(_conn_ctx->local_settings().stream_window_size) / (_conn_ctx->VolatilePendingStreamSize() + 1)) {
         if (acc > _conn_ctx->local_settings().stream_window_size) {
             LOG(ERROR) << "Fail to satisfy the stream-level flow control policy";
             return MakeH2Error(H2_FLOW_CONTROL_ERROR, frame_head.stream_id);