diff --git a/engine/openbor.h b/engine/openbor.h
index 57a5af2f7..02e0f734b 100644
--- a/engine/openbor.h
+++ b/engine/openbor.h
@@ -603,6 +603,18 @@ typedef enum
     BOSS_SLOW_ON
 } e_boss_slow_flag;
 
+typedef enum
+{
+    DAMAGE_FROM_ENEMY_OFF,
+    DAMAGE_FROM_ENEMY_ON
+} e_damage_from_enemy_flag;
+
+typedef enum
+{
+    DAMAGE_FROM_PLAYER_OFF,
+    DAMAGE_FROM_PLAYER_ON
+} e_damage_from_player_flag;
+
 typedef enum
 {
     LEVEL_PROP_AUTO_SCROLL_DIRECTION,           // int bgdir;