diff --git a/common/pb/event_reveal_cards.proto b/common/pb/event_reveal_cards.proto
index f746ff279..294852631 100644
--- a/common/pb/event_reveal_cards.proto
+++ b/common/pb/event_reveal_cards.proto
@@ -6,7 +6,7 @@ message Event_RevealCards {
 		optional Event_RevealCards ext = 2006;
 	}
 	optional string zone_name = 1;
-	optional sint32 card_id = 2;
-	optional sint32 other_player_id = 3;
+	optional sint32 card_id = 2 [default = -1];
+	optional sint32 other_player_id = 3 [default = -1];
 	repeated ServerInfo_Card cards = 4;
 }