diff --git a/common/constants.cc b/common/constants.cc
index fc6df37..f138ce3 100644
--- a/common/constants.cc
+++ b/common/constants.cc
@@ -94,5 +94,7 @@
 const char kPayloadPropertyFileHash[] = "FILE_HASH";
 const char kPayloadPropertyMetadataSize[] = "METADATA_SIZE";
 const char kPayloadPropertyMetadataHash[] = "METADATA_HASH";
+const char kPayloadPropertyAuthorization[] = "AUTHORIZATION";
+const char kPayloadPropertyUserAgent[] = "USER_AGENT";
 
 }  // namespace chromeos_update_engine