diff --git a/engine/battle/core.asm b/engine/battle/core.asm
index e12299b48..919de01cf 100644
--- a/engine/battle/core.asm
+++ b/engine/battle/core.asm
@@ -2820,6 +2820,9 @@ SelectMenuItem_CursorDown:
 	jp SelectMenuItem
 
 Func_3d4f5:
+IF DEF(_DEBUG)
+	ASSERT BIT_START == BIT_TRAINER_BATTLE
+ENDC
 	bit BIT_TRAINER_BATTLE, a
 	ld a, $0
 	jr nz, .asm_3d4fd