diff --git a/common/quiche_data_reader.cc b/common/quiche_data_reader.cc
index 3445013..2242fea 100644
--- a/common/quiche_data_reader.cc
+++ b/common/quiche_data_reader.cc
@@ -10,6 +10,7 @@
 #include "net/third_party/quiche/src/common/platform/api/quiche_logging.h"
 #include "net/third_party/quiche/src/common/platform/api/quiche_str_cat.h"
 #include "net/third_party/quiche/src/common/platform/api/quiche_string_piece.h"
+#include "net/third_party/quiche/src/common/platform/api/quiche_text_utils.h"
 
 namespace quiche {
 
@@ -119,6 +120,15 @@
   return ReadBytes(tag, sizeof(*tag));
 }
 
+bool QuicheDataReader::ReadDecimal64(size_t num_digits, uint64_t* result) {
+  quiche::QuicheStringPiece digits;
+  if (!ReadStringPiece(&digits, num_digits)) {
+    return false;
+  }
+
+  return QuicheTextUtils::StringToUint64(digits, result);
+}
+
 quiche::QuicheStringPiece QuicheDataReader::ReadRemainingPayload() {
   quiche::QuicheStringPiece payload = PeekRemainingPayload();
   pos_ = len_;