diff --git a/player.h b/player.h
--- a/player.h
+++ b/player.h
@@ -194,6 +194,7 @@ typedef struct Player {
 	bool renew_keep_length;
 	int16 engine_renew_months;
 	uint32 engine_renew_money;
+	uint16 num_engines[TOTAL_NUM_ENGINES]; // caches the number of engines of each type the player owns (no need to save this)
 } Player;
 
 uint16 GetDrawStringPlayerColor(PlayerID player);