diff --git a/code/modules/organs/organ_external.dm b/code/modules/organs/organ_external.dm
index db9107a3b85..7614a6eaaa8 100644
--- a/code/modules/organs/organ_external.dm
+++ b/code/modules/organs/organ_external.dm
@@ -407,8 +407,8 @@ Note that amputating the affected organ does in fact remove the infection from t
 				owner.adjustToxLoss(1)
 
 	if(germ_level >= INFECTION_LEVEL_TWO && antibiotics < 5)
-		//spread the infection
-		var/datum/organ/internal/target_organ	//make internal organs become infected one at a time instead of all at once
+		//spread the infection to internal organs
+		var/datum/organ/internal/target_organ = null	//make internal organs become infected one at a time instead of all at once
 		for (var/datum/organ/internal/I in internal_organs)
 			if (I.germ_level > 0 && I.germ_level < min(germ_level, INFECTION_LEVEL_TWO))	//once the organ reaches whatever we can give it, or level two, switch to a different one
 				if (!target_organ || I.germ_level > target_organ.germ_level)	//choose the organ with the highest germ_level
@@ -420,11 +420,14 @@ Note that amputating the affected organ does in fact remove the infection from t
 			for (var/datum/organ/internal/I in internal_organs)
 				if (I.germ_level < germ_level)
 					candidate_organs += I
-			target_organ = pick(candidate_organs)
+			if (candidate_organs.len)
+				target_organ = pick(candidate_organs)
 		
-		target_organ.germ_level++
+		if (target_organ)
+			target_organ.germ_level++
 
-		if (children)	//To child organs
+		//spread the infection to child and parent organs
+		if (children)
 			for (var/datum/organ/external/child in children)
 				if (child.germ_level < germ_level && !(child.status & ORGAN_ROBOT))
 					if (child.germ_level < INFECTION_LEVEL_ONE*2 || prob(30))