diff --git a/llvm/utils/gn/secondary/lldb/tools/lldb-dap/BUILD.gn b/llvm/utils/gn/secondary/lldb/tools/lldb-dap/BUILD.gn
index c8dc997e8e03..9c2768f457ff 100644
--- a/llvm/utils/gn/secondary/lldb/tools/lldb-dap/BUILD.gn
+++ b/llvm/utils/gn/secondary/lldb/tools/lldb-dap/BUILD.gn
@@ -74,6 +74,7 @@ static_library("lib") {
     "Protocol/ProtocolBase.cpp",
     "Protocol/ProtocolRequests.cpp",
     "Protocol/ProtocolTypes.cpp",
+    "ProtocolUtils.cpp",
     "RunInTerminal.cpp",
     "SourceBreakpoint.cpp",
     "Transport.cpp",