diff --git a/quic/core/crypto/null_encrypter.cc b/quic/core/crypto/null_encrypter.cc
index 69db96d..4ad9b2a 100644
--- a/quic/core/crypto/null_encrypter.cc
+++ b/quic/core/crypto/null_encrypter.cc
@@ -58,7 +58,7 @@
 }
 
 std::string NullEncrypter::GenerateHeaderProtectionMask(
-    QuicStringPiece sample) {
+    QuicStringPiece /*sample*/) {
   return std::string(5, 0);
 }