diff --git a/src/google/protobuf/compiler/command_line_interface.cc b/src/google/protobuf/compiler/command_line_interface.cc
index d5e77ae632f3b..d6f4e2e98367d 100644
--- a/src/google/protobuf/compiler/command_line_interface.cc
+++ b/src/google/protobuf/compiler/command_line_interface.cc
@@ -1766,6 +1766,8 @@ bool CommandLineInterface::MakeInputsBeProtoPathRelative(
 bool CommandLineInterface::ExpandArgumentFile(
     const char* file, std::vector<std::string>* arguments) {
 
+// On windows to force ifstream to handle proper utr-8, we need to convert to proper supported utf8 wstring.
+// If we dont then the file can't be opened.
 #ifdef _MSC_VER
   // Convert the file name to wide chars.
   int size = MultiByteToWideChar(CP_UTF8, 0, file, strlen(file), NULL, 0);