diff --git a/code/modules/organs/organ.dm b/code/modules/organs/organ.dm
index d175fb42c53..19c1e52e860 100644
--- a/code/modules/organs/organ.dm
+++ b/code/modules/organs/organ.dm
@@ -251,23 +251,25 @@ INITIALIZE_IMMEDIATE(/obj/item/organ)
 
 /obj/item/organ/proc/handle_rejection()
 	// Process unsuitable transplants.
-	if(dna)
-		if(!rejecting)
-			if(blood_incompatible(dna.b_type, owner.dna.b_type, species, owner.species))
-				rejecting = 1
-		else
-			rejecting++ //Rejection severity increases over time.
-			if(rejecting % 10 == 0) //Only fire every ten rejection ticks.
-				switch(rejecting)
-					if(1 to 50)
-						germ_level++
-					if(51 to 200)
-						germ_level += rand(1,2)
-					if(201 to 500)
-						germ_level += rand(2,3)
-					if(501 to INFINITY)
-						germ_level += rand(3,5)
-						owner.reagents.add_reagent(/singleton/reagent/toxin, rand(1,2))
+	if(!owner || !owner.dna || !dna)
+		return
+
+	if(!rejecting && blood_incompatible(dna.b_type, owner.dna.b_type, species, owner.species))
+		rejecting = 1
+		return
+
+	rejecting++ //Rejection severity increases over time.
+	if(rejecting % 10 == 0) //Only fire every ten rejection ticks.
+		switch(rejecting)
+			if(1 to 50)
+				germ_level++
+			if(51 to 200)
+				germ_level += rand(1,2)
+			if(201 to 500)
+				germ_level += rand(2,3)
+			if(501 to INFINITY)
+				germ_level += rand(3,5)
+				owner.reagents.add_reagent(/singleton/reagent/toxin, rand(1,2))
 
 /obj/item/organ/proc/receive_chem(chemical as obj)
 	return 0
diff --git a/html/changelogs/hellfirejag-organ-transplant-runtime.yml b/html/changelogs/hellfirejag-organ-transplant-runtime.yml
new file mode 100644
index 00000000000..4d42a97ba84
--- /dev/null
+++ b/html/changelogs/hellfirejag-organ-transplant-runtime.yml
@@ -0,0 +1,4 @@
+author: Hellfirejag
+delete-after: True
+changes:
+  - bugfix: "Fixed a runtime error in organ rejection."