diff --git a/code/datums/ammo/ammo.dm b/code/datums/ammo/ammo.dm
index a59290ab5f51..f2a7dc8ffc81 100644
--- a/code/datums/ammo/ammo.dm
+++ b/code/datums/ammo/ammo.dm
@@ -173,6 +173,10 @@
 		living_mob.apply_stamina_damage(fired_projectile.ammo.damage, fired_projectile.def_zone, ARMOR_BULLET)
 
 /datum/ammo/proc/slowdown(mob/living/living_mob, obj/projectile/fired_projectile)
+	if(isxeno(living_mob))
+		var/mob/living/carbon/xenomorph/xeno = living_mob
+		if(xeno.caste.tier > 2 || (xeno.caste.tier == 0 && xeno.mob_size >= MOB_SIZE_BIG))
+			return //tier 3 and big tier 0 (like queen) are not affected
 	if(iscarbonsizexeno(living_mob))
 		var/mob/living/carbon/xenomorph/target = living_mob
 		target.apply_effect(1, SUPERSLOW)