diff --git a/PKHeX.Core/Legality/RNG/MethodFinder.cs b/PKHeX.Core/Legality/RNG/MethodFinder.cs
index c3007e3fb..472a8470d 100644
--- a/PKHeX.Core/Legality/RNG/MethodFinder.cs
+++ b/PKHeX.Core/Legality/RNG/MethodFinder.cs
@@ -266,8 +266,9 @@ private static bool GetG5MGShinyMatch(PKM pk, uint pid, out PIDIV pidiv)
             // generation 5 shiny PIDs
             if (low <= 0xFF)
             {
-                var high = pid >> 16;
-                if (((pk.TID ^ pk.SID ^ low) - high & 0xFFFE) == 0)
+                var av = (pid >> 16) & 1;
+                var genPID = PIDGenerator.GetMG5ShinyPID(low, av, pk.TID, pk.SID);
+                if (genPID == pid)
                 {
                     pidiv = new PIDIV {NoSeed = true, Type = PIDType.G5MGShiny};
                     return true;
diff --git a/PKHeX.Core/Legality/RNG/PIDGenerator.cs b/PKHeX.Core/Legality/RNG/PIDGenerator.cs
index 68406fa2e..babb1de77 100644
--- a/PKHeX.Core/Legality/RNG/PIDGenerator.cs
+++ b/PKHeX.Core/Legality/RNG/PIDGenerator.cs
@@ -142,5 +142,13 @@ public static void SetValuesFromSeed(PKM pk, PIDType type, uint seed)
                     break;
             }
         }
+
+        public static uint GetMG5ShinyPID(uint gval, uint av, int TID, int SID)
+        {
+            uint PID = (uint)((TID ^ SID ^ gval) << 16 | gval);
+            if ((PID & 0x10000) != av << 16)
+                PID ^= 0x10000;
+            return PID;
+        }
     }
 }
diff --git a/PKHeX.Core/MysteryGifts/PGF.cs b/PKHeX.Core/MysteryGifts/PGF.cs
index 71bc47848..4b26e8380 100644
--- a/PKHeX.Core/MysteryGifts/PGF.cs
+++ b/PKHeX.Core/MysteryGifts/PGF.cs
@@ -269,13 +269,11 @@ public override PKM ConvertToPKM(SaveFile SAV)
                 if (PIDType == 2) // Force Shiny
                 {
                     uint gb = pk.PID & 0xFF;
-                    pk.PID = (uint)((gb ^ pk.TID ^ pk.SID) << 16) | gb;
-                    // double check forced ability
-                    if (av == 1) pk.PID |= 0x10001; else pk.PID &= 0xFFFEFFFE;
+                    pk.PID = PIDGenerator.GetMG5ShinyPID(gb, (uint)av, pk.TID, pk.SID);
                 }
                 else if (PIDType != 1) // Force Not Shiny
                 {
-                    if (((pk.PID >> 16) ^ (pk.PID & 0xffff) ^ pk.SID ^ pk.TID) < 8)
+                    if (pk.IsShiny)
                         pk.PID ^= 0x10000000;
                 }
             }
diff --git a/PKHeX.Core/PKM/PKM.cs b/PKHeX.Core/PKM/PKM.cs
index af4bf9297..e37c90a20 100644
--- a/PKHeX.Core/PKM/PKM.cs
+++ b/PKHeX.Core/PKM/PKM.cs
@@ -333,13 +333,21 @@ public int GenNumber
         public int MarkHeart       { get => Markings[3]; set { var marks = Markings; marks[3] = value; Markings = marks; } }
         public int MarkStar        { get => Markings[4]; set { var marks = Markings; marks[4] = value; Markings = marks; } }
         public int MarkDiamond     { get => Markings[5]; set { var marks = Markings; marks[5] = value; Markings = marks; } }
-        protected int SwapBits(int n, int p1, int p2)
+        /// <summary>
+        /// Swaps bits at a given position
+        /// </summary>
+        /// <param name="value">Value to swap bits for</param>
+        /// <param name="p1">Position of first bit to be swapped</param>
+        /// <param name="p2">Position of second bit to be swapped</param>
+        /// <remarks>Generation 3 marking values are swapped (Square-Triangle, instead of Triangle-Square).</remarks>
+        /// <returns>Swapped bits value</returns>
+        protected static int SwapBits(int value, int p1, int p2)
         {
-            int bit1 = (n >> p1) & 1;
-            int bit2 = (n >> p2) & 1;
+            int bit1 = (value >> p1) & 1;
+            int bit2 = (value >> p2) & 1;
             int x = bit1 ^ bit2;
             x = (x << p1) | (x << p2);
-            return n ^ x;
+            return value ^ x;
         }
         public string ShowdownText => ShowdownSet.GetShowdownText(this);
         public string[] QRText => this.GetQRLines();