diff --git a/code/__defines/species_languages.dm b/code/__defines/species_languages.dm
index bd0d02ae80..5cfb5f37d0 100644
--- a/code/__defines/species_languages.dm
+++ b/code/__defines/species_languages.dm
@@ -9,6 +9,7 @@
 #define NO_HALLUCINATION  0x80	 // Don't hallucinate, ever
 #define NO_BLOOD		  0x100  // Never bleed, never show blood amount
 #define UNDEAD			  0x200	 // Various things that living things don't do, mostly for skeletons
+#define NO_INFECT		  0x400  // Don't allow infections in limbs or organs, similar to IS_PLANT, without other strings.
 // unused: 0x8000 - higher than this will overflow
 
 // Species spawn flags
diff --git a/code/modules/mob/living/carbon/human/species/station/prometheans.dm b/code/modules/mob/living/carbon/human/species/station/prometheans.dm
index 7d1ed3bb0e..5201047761 100644
--- a/code/modules/mob/living/carbon/human/species/station/prometheans.dm
+++ b/code/modules/mob/living/carbon/human/species/station/prometheans.dm
@@ -20,7 +20,7 @@ var/datum/species/shapeshifter/promethean/prometheans
 	bump_flag =        SLIME
 	swap_flags =       MONKEY|SLIME|SIMPLE_ANIMAL
 	push_flags =       MONKEY|SLIME|SIMPLE_ANIMAL
-	flags =            NO_SCAN | NO_SLIP | NO_MINOR_CUT | NO_HALLUCINATION
+	flags =            NO_SCAN | NO_SLIP | NO_MINOR_CUT | NO_HALLUCINATION | NO_INFECT
 	appearance_flags = HAS_SKIN_COLOR | HAS_EYE_COLOR | HAS_HAIR_COLOR | RADIATION_GLOWS | HAS_UNDERWEAR
 	spawn_flags		 = SPECIES_CAN_JOIN | SPECIES_IS_WHITELISTED
 	health_hud_intensity = 2
diff --git a/code/modules/organs/organ.dm b/code/modules/organs/organ.dm
index 77706b9517..7f4599ecdd 100644
--- a/code/modules/organs/organ.dm
+++ b/code/modules/organs/organ.dm
@@ -108,7 +108,7 @@ var/list/organ_cache = list()
 	if(preserved)
 		return
 	//Process infections
-	if ((robotic >= ORGAN_ROBOT) || (owner && owner.species && (owner.species.flags & IS_PLANT)))
+	if(robotic >= ORGAN_ROBOT || (owner && owner.species && (owner.species.flags & IS_PLANT || (owner.species.flags & NO_INFECT))))
 		germ_level = 0
 		return
 
diff --git a/code/modules/organs/organ_external.dm b/code/modules/organs/organ_external.dm
index 070e3087db..17d1025fde 100644
--- a/code/modules/organs/organ_external.dm
+++ b/code/modules/organs/organ_external.dm
@@ -603,7 +603,7 @@ Note that amputating the affected organ does in fact remove the infection from t
 */
 /obj/item/organ/external/proc/update_germs()
 
-	if(robotic >= ORGAN_ROBOT || (owner.species && owner.species.flags & IS_PLANT)) //Robotic limbs shouldn't be infected, nor should nonexistant limbs.
+	if(robotic >= ORGAN_ROBOT || (owner.species && (owner.species.flags & IS_PLANT || (owner.species.flags & NO_INFECT)))) //Robotic limbs shouldn't be infected, nor should nonexistant limbs.
 		germ_level = 0
 		return