diff --git a/PKHeX.Core/Legality/Tables/Tables8.cs b/PKHeX.Core/Legality/Tables/Tables8.cs
index 668893dc0..dc75072b9 100644
--- a/PKHeX.Core/Legality/Tables/Tables8.cs
+++ b/PKHeX.Core/Legality/Tables/Tables8.cs
@@ -181,7 +181,7 @@ public static partial class Legal
             1105, 1106, 1107, 1108,
         };
 
-        internal static readonly ushort[] HeldItems_SWSH = new ushort[1].Concat(Pouch_Items_SWSH).Concat(Pouch_Berries_SWSH).Concat(Pouch_Medicine_SWSH).Concat(TR_SWSH).ToArray();
+        internal static readonly ushort[] HeldItems_SWSH = ArrayUtil.ConcatAll(new ushort[1], Pouch_Items_SWSH, Pouch_Berries_SWSH, Pouch_Medicine_SWSH, TR_SWSH, Pouch_Treasure_SWSH);
 
         internal static readonly HashSet<int> WildPokeballs8 = new HashSet<int> {
             (int)Ball.Poke,
diff --git a/PKHeX.Core/Util/ArrayUtil.cs b/PKHeX.Core/Util/ArrayUtil.cs
index 0d1c3df6d..89ce5c54f 100644
--- a/PKHeX.Core/Util/ArrayUtil.cs
+++ b/PKHeX.Core/Util/ArrayUtil.cs
@@ -160,5 +160,23 @@ public static int CopyTo<T>(this IEnumerable<T> list, IList<T> dest, int start =
             }
             return ctr - start;
         }
+
+        internal static T[] ConcatAll<T>(params T[][] arr)
+        {
+            int len = 0;
+            foreach (var a in arr)
+                len += a.Length;
+
+            var result = new T[len];
+
+            int ctr = 0;
+            for (int i = 0; i < arr.Length; i++)
+            {
+                arr[i].CopyTo(result, ctr);
+                ctr += arr[i].Length;
+            }
+
+            return result;
+        }
     }
 }
\ No newline at end of file