diff --git a/payload_constants.h b/payload_constants.h
index 21dab00..81bc36a 100644
--- a/payload_constants.h
+++ b/payload_constants.h
@@ -21,6 +21,8 @@
 
 #include <limits>
 
+#include "update_engine/update_metadata.pb.h"
+
 namespace chromeos_update_engine {
 
 // The major version used by Chrome OS.
@@ -52,6 +54,9 @@
 // section of blocks not present on disk on a sparse file.
 const uint64_t kSparseHole = std::numeric_limits<uint64_t>::max();
 
+// Return the name of the operation type.
+const char* InstallOperationTypeName(InstallOperation_Type op_type);
+
 }  // namespace chromeos_update_engine
 
 #endif  // UPDATE_ENGINE_PAYLOAD_CONSTANTS_H_