diff --git a/quic/test_tools/quic_test_utils.cc b/quic/test_tools/quic_test_utils.cc
index 02a0f0f..12befe4 100644
--- a/quic/test_tools/quic_test_utils.cc
+++ b/quic/test_tools/quic_test_utils.cc
@@ -1517,7 +1517,7 @@
 
 bool WriteServerVersionNegotiationProbeResponse(
     char* packet_bytes,
-    QuicByteCount* packet_length_out,
+    size_t* packet_length_out,
     const char* source_connection_id_bytes,
     uint8_t source_connection_id_length) {
   if (packet_bytes == nullptr) {
@@ -1552,7 +1552,7 @@
 
 bool ParseClientVersionNegotiationProbePacket(
     const char* packet_bytes,
-    QuicByteCount packet_length,
+    size_t packet_length,
     char* destination_connection_id_bytes,
     uint8_t* destination_connection_id_length_out) {
   if (packet_bytes == nullptr) {
diff --git a/quic/test_tools/quic_test_utils.h b/quic/test_tools/quic_test_utils.h
index c6a37f0..c4e440b 100644
--- a/quic/test_tools/quic_test_utils.h
+++ b/quic/test_tools/quic_test_utils.h
@@ -2153,7 +2153,7 @@
 // WriteClientVersionNegotiationProbePacket.
 bool ParseClientVersionNegotiationProbePacket(
     const char* packet_bytes,
-    QuicByteCount packet_length,
+    size_t packet_length,
     char* destination_connection_id_bytes,
     uint8_t* destination_connection_id_length_out);
 
@@ -2167,7 +2167,7 @@
 // bytes of memory.
 bool WriteServerVersionNegotiationProbeResponse(
     char* packet_bytes,
-    QuicByteCount* packet_length_out,
+    size_t* packet_length_out,
     const char* source_connection_id_bytes,
     uint8_t source_connection_id_length);