diff --git a/cpp/utils.cc b/cpp/utils.cc
index 7f55a23..0862657 100644
--- a/cpp/utils.cc
+++ b/cpp/utils.cc
@@ -24,6 +24,9 @@ bool ReadCsvMetaFile(const std::string& filename,
         for (int i = 0; i < descriptor->field_count(); ++i) {
             const google::protobuf::FieldDescriptor* field_desc = descriptor->field(i);
             const std::string& field_name = field_desc->name();
+            if (field_name.empty() || field_name[0] == '_') {
+                continue;
+            }
 
             switch (field_desc->cpp_type()) {
             case google::protobuf::FieldDescriptor::CPPTYPE_STRING: