diff --git a/engine/battle/move_effects/conversion2.asm b/engine/battle/move_effects/conversion2.asm
index 7fefbfee5..074ca93ba 100644
--- a/engine/battle/move_effects/conversion2.asm
+++ b/engine/battle/move_effects/conversion2.asm
@@ -27,7 +27,7 @@ BattleCommand_Conversion2: ; 359e6
 
 .loop
 	call BattleRandom
-	and $1f
+	maskbits NUM_TYPES
 	cp UNUSED_TYPES
 	jr c, .okay
 	cp UNUSED_TYPES_END