diff --git a/buffet/commands/schema_constants.cc b/buffet/commands/schema_constants.cc
index 2868a06..6aaf780 100644
--- a/buffet/commands/schema_constants.cc
+++ b/buffet/commands/schema_constants.cc
@@ -52,6 +52,8 @@
 const char kCommand_Results[] = "results";
 const char kCommand_State[] = "state";
 const char kCommand_Progress[] = "progress";
+const char kCommand_ErrorCode[] = "error.code";
+const char kCommand_ErrorMessage[] = "error.message";
 
 const char kCommand_Visibility[] = "visibility";
 const char kCommand_Visibility_None[] = "none";