diff --git a/data/battle_scripts_1.s b/data/battle_scripts_1.s
index 007d3649c4..522ffb7014 100644
--- a/data/battle_scripts_1.s
+++ b/data/battle_scripts_1.s
@@ -1242,13 +1242,13 @@ BattleScript_ShellSmashTryDef::
 	setbyte sSTAT_ANIM_PLAYED, FALSE
 	playstatchangeanimation BS_ATTACKER, BIT_DEF | BIT_SPDEF, STAT_CHANGE_NEGATIVE | STAT_CHANGE_CANT_PREVENT
 	setstatchanger STAT_DEF, 1, TRUE
-	statbuffchange MOVE_EFFECT_AFFECTS_USER | STAT_BUFF_ALLOW_PTR, BattleScript_ShellSmashTrySpDef
+	statbuffchange MOVE_EFFECT_AFFECTS_USER | STAT_BUFF_ALLOW_PTR | MOVE_EFFECT_CERTAIN, BattleScript_ShellSmashTrySpDef
 	jumpifbyte CMP_EQUAL, cMULTISTRING_CHOOSER, B_MSG_STAT_WONT_INCREASE, BattleScript_ShellSmashTrySpDef
 	printfromtable gStatUpStringIds
 	waitmessage B_WAIT_TIME_LONG
 BattleScript_ShellSmashTrySpDef:
 	setstatchanger STAT_SPDEF, 1, TRUE
-	statbuffchange MOVE_EFFECT_AFFECTS_USER | STAT_BUFF_ALLOW_PTR, BattleScript_ShellSmashTryAttack
+	statbuffchange MOVE_EFFECT_AFFECTS_USER | STAT_BUFF_ALLOW_PTR | MOVE_EFFECT_CERTAIN, BattleScript_ShellSmashTryAttack
 	jumpifbyte CMP_EQUAL, cMULTISTRING_CHOOSER, B_MSG_STAT_WONT_INCREASE, BattleScript_ShellSmashTryAttack
 	printfromtable gStatUpStringIds
 	waitmessage B_WAIT_TIME_LONG