From 6f03bd97cf6819f3a39ee1f43a8a7e104bdba397 Mon Sep 17 00:00:00 2001
From: Guti <32563288+TheCaramelion@users.noreply.github.com>
Date: Tue, 3 Feb 2026 19:55:34 +0100
Subject: [PATCH] Fix (#19124)

---
 code/datums/diseases/advance/advance.dm | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/code/datums/diseases/advance/advance.dm b/code/datums/diseases/advance/advance.dm
index 5e3e506c98..255a5bbb4f 100644
--- a/code/datums/diseases/advance/advance.dm
+++ b/code/datums/diseases/advance/advance.dm
@@ -302,7 +302,7 @@ GLOBAL_LIST_INIT(advance_cures, list(
 
 // Randomly generate a symptom, has a chance to lose or gain a symptom.
 /datum/disease/advance/proc/Evolve(min_level, max_level, ignore_mutable = FALSE)
-	if(!global_flag_check(virus_modifiers, IMMUTABLE) && !ignore_mutable)
+	if(global_flag_check(virus_modifiers, IMMUTABLE) && !ignore_mutable)
 		return
 	var/s = safepick(GenerateSymptoms(min_level, max_level, 1))
 	if(s)
@@ -311,8 +311,8 @@ GLOBAL_LIST_INIT(advance_cures, list(
 	return
 
 // Randomly generates a symptom from a given list, has a chance to lose or gain a symptom.
-/datum/disease/advance/proc/PickyEvolve(var/list/datum/symptom/D, ignore_mutable)
-	if(!global_flag_check(virus_modifiers, IMMUTABLE) && !ignore_mutable)
+/datum/disease/advance/proc/PickyEvolve(list/datum/symptom/D, ignore_mutable = FALSE)
+	if(global_flag_check(virus_modifiers, IMMUTABLE) && !ignore_mutable)
 		return
 	var/s = safepick(D)
 	if(s)
@@ -322,7 +322,7 @@ GLOBAL_LIST_INIT(advance_cures, list(
 
 // Randomly remove a symptom.
 /datum/disease/advance/proc/Devolve(ignore_mutable = FALSE)
-	if(!global_flag_check(virus_modifiers, IMMUTABLE) && !ignore_mutable)
+	if(global_flag_check(virus_modifiers, IMMUTABLE) && !ignore_mutable)
 		return
 	if(length(symptoms) > 1)
 		var/s = safepick(symptoms)
@@ -333,7 +333,7 @@ GLOBAL_LIST_INIT(advance_cures, list(
 
 // Randomly neuter a symptom.
 /datum/disease/advance/proc/Neuter(ignore_mutable = FALSE)
-	if(!global_flag_check(virus_modifiers, IMMUTABLE) && !ignore_mutable)
+	if(global_flag_check(virus_modifiers, IMMUTABLE) && !ignore_mutable)
 		return
 	if(symptoms.len)
 		var/s = safepick(symptoms)
@@ -442,7 +442,7 @@ GLOBAL_LIST_INIT(advance_cures, list(
 	var/list/diseases = list()
 
 	for(var/datum/disease/advance/A in D_list)
-		if(!global_flag_check(A.virus_modifiers, IMMUTABLE))
+		if(global_flag_check(A.virus_modifiers, IMMUTABLE))
 			return
 		diseases += A.Copy()
 
@@ -537,9 +537,9 @@ GLOBAL_LIST_INIT(advance_cures, list(
 
 		return TRUE
 
-/datum/disease/advance/infect(var/mob/living/infectee, make_copy = TRUE)
+/datum/disease/advance/infect(mob/living/infectee, make_copy = TRUE)
 	var/datum/disease/advance/A = make_copy ? Copy() : src
-	if(!initial && global_flag_check(A.virus_modifiers, IMMUTABLE) && (spread_flags & DISEASE_SPREAD_FLUIDS))
+	if(!initial && !global_flag_check(A.virus_modifiers, IMMUTABLE) && (spread_flags & DISEASE_SPREAD_FLUIDS))
 		var/minimum = 1
 		if(prob(clamp(35-(A.resistance + A.stealth - A.speed), 0, 50) * (A.mutability)))
 			if(infectee.job == JOB_CLOWN || infectee.job == JOB_MIME || prob(1))