diff --git a/code/datums/diseases/advance/symptoms/oxygen.dm b/code/datums/diseases/advance/symptoms/oxygen.dm
index 15cdb2b8b1f..630f2e2d7fb 100644
--- a/code/datums/diseases/advance/symptoms/oxygen.dm
+++ b/code/datums/diseases/advance/symptoms/oxygen.dm
@@ -50,7 +50,7 @@
 	if(!.)
 		return FALSE
 	var/mob/living/carbon/M = A.affected_mob
-	if(A.stage > 4)
+	if(A.stage >= 4)
 		ADD_TRAIT(M, TRAIT_NOBREATH, DISEASE_TRAIT)
 	else
 		REMOVE_TRAIT(M, TRAIT_NOBREATH, DISEASE_TRAIT)