diff --git a/lldb/tools/lldb-dap/DAP.h b/lldb/tools/lldb-dap/DAP.h
index a164cc484f4be..c3cc87b4534c6 100644
--- a/lldb/tools/lldb-dap/DAP.h
+++ b/lldb/tools/lldb-dap/DAP.h
@@ -133,6 +133,7 @@ struct DAP final : public DAPTransport::MessageHandler {
   bool configuration_done;
 
   bool waiting_for_run_in_terminal = false;
+  std::mutex call_mutex;
   ProgressEventReporter progress_event_reporter;
 
   /// Keep track of the last stop thread index IDs as threads won't go away
@@ -140,7 +141,6 @@ struct DAP final : public DAPTransport::MessageHandler {
   llvm::DenseSet<lldb::tid_t> thread_ids;
 
   protocol::Id seq = 0;
-  std::mutex call_mutex;
   llvm::SmallDenseMap<int64_t, std::unique_ptr<ResponseHandler>>
       inflight_reverse_requests;
   ReplMode repl_mode;