diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c
index 204aa95045..e1191a7564 100644
--- a/src/backend/access/transam/multixact.c
+++ b/src/backend/access/transam/multixact.c
@@ -799,7 +799,8 @@ MultiXactIdCreateFromMembers(int nmembers, MultiXactMember *members)
 			if (ISUPDATE_from_mxstatus(members[i].status))
 			{
 				if (has_update)
-					elog(ERROR, "new multixact has more than one updating member");
+					elog(ERROR, "new multixact has more than one updating member: %s",
+						 mxid_to_string(InvalidMultiXactId, nmembers, members));
 				has_update = true;
 			}
 		}