diff --git a/PKHeX.Core/Legality/Encounters/EncounterSlot/EncounterSlot8GO.cs b/PKHeX.Core/Legality/Encounters/EncounterSlot/EncounterSlot8GO.cs
index 2441b073e..cc2018d38 100644
--- a/PKHeX.Core/Legality/Encounters/EncounterSlot/EncounterSlot8GO.cs
+++ b/PKHeX.Core/Legality/Encounters/EncounterSlot/EncounterSlot8GO.cs
@@ -38,9 +38,9 @@ public bool IsWithinStartEnd(int y, int m, int d)
         public bool IsWithinStartEnd(int stamp)
         {
             if (End == 0)
-                return stamp >= Start;
+                return Start <= stamp;
             if (Start == 0)
-                return stamp <= Start;
+                return stamp <= End;
             return Start <= stamp && stamp <= End;
         }