diff --git a/src/libraries/System.Private.CoreLib/src/System/Guid.cs b/src/libraries/System.Private.CoreLib/src/System/Guid.cs
index e4bea80bf69bf..999e82e81377e 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Guid.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Guid.cs
@@ -423,29 +423,15 @@ public static bool TryParseExact(ReadOnlySpan<char> input, [StringSyntax(StringS
             input = input.Trim();
 
             var parseResult = new GuidResult(GuidParseThrowStyle.None);
-            bool success = false;
-            switch ((char)(format[0] | 0x20))
-            {
-                case 'd':
-                    success = TryParseExactD(input, ref parseResult);
-                    break;
-
-                case 'n':
-                    success = TryParseExactN(input, ref parseResult);
-                    break;
-
-                case 'b':
-                    success = TryParseExactB(input, ref parseResult);
-                    break;
-
-                case 'p':
-                    success = TryParseExactP(input, ref parseResult);
-                    break;
-
-                case 'x':
-                    success = TryParseExactX(input, ref parseResult);
-                    break;
-            }
+            bool success = (format[0] | 0x20) switch
+            {
+                'd' => TryParseExactD(input, ref parseResult),
+                'n' => TryParseExactN(input, ref parseResult),
+                'b' => TryParseExactB(input, ref parseResult),
+                'p' => TryParseExactP(input, ref parseResult),
+                'x' => TryParseExactX(input, ref parseResult),
+                _ => false
+            };
 
             if (success)
             {
@@ -1108,24 +1094,6 @@ private static unsafe int HexsToChars<TChar>(TChar* guidChars, int a, int b) whe
             return 4;
         }
 
-        private static unsafe int HexsToCharsHexOutput<TChar>(TChar* guidChars, int a, int b) where TChar : unmanaged, IUtfChar<TChar>
-        {
-            guidChars[0] = TChar.CastFrom('0');
-            guidChars[1] = TChar.CastFrom('x');
-
-            guidChars[2] = TChar.CastFrom(HexConverter.ToCharLower(a >> 4));
-            guidChars[3] = TChar.CastFrom(HexConverter.ToCharLower(a));
-
-            guidChars[4] = TChar.CastFrom(',');
-            guidChars[5] = TChar.CastFrom('0');
-            guidChars[6] = TChar.CastFrom('x');
-
-            guidChars[7] = TChar.CastFrom(HexConverter.ToCharLower(b >> 4));
-            guidChars[8] = TChar.CastFrom(HexConverter.ToCharLower(b));
-
-            return 9;
-        }
-
         // Returns the guid in "registry" format.
         public override string ToString() => ToString("d", null);
 
@@ -1379,49 +1347,67 @@ internal unsafe bool TryFormatCore<TChar>(Span<TChar> destination, out int chars
             return true;
         }
 
-        private unsafe bool TryFormatX<TChar>(Span<TChar> destination, out int charsWritten) where TChar : unmanaged, IUtfChar<TChar>
+        private bool TryFormatX<TChar>(Span<TChar> dest, out int charsWritten) where TChar : unmanaged, IUtfChar<TChar>
         {
-            if (destination.Length < 68)
+            if (dest.Length < 68)
             {
                 charsWritten = 0;
                 return false;
             }
+
+            // {0xdddddddd,0xdddd,0xdddd,{0xdd,0xdd,0xdd,0xdd,0xdd,0xdd,0xdd,0xdd}}
+            dest[0]  = TChar.CastFrom('{');
+            dest[1]  = TChar.CastFrom('0');
+            dest[2]  = TChar.CastFrom('x');
+            dest[3]  = TChar.CastFrom(HexConverter.ToCharLower(_a >> 28));
+            dest[4]  = TChar.CastFrom(HexConverter.ToCharLower(_a >> 24));
+            dest[5]  = TChar.CastFrom(HexConverter.ToCharLower(_a >> 20));
+            dest[6]  = TChar.CastFrom(HexConverter.ToCharLower(_a >> 16));
+            dest[7]  = TChar.CastFrom(HexConverter.ToCharLower(_a >> 12));
+            dest[8]  = TChar.CastFrom(HexConverter.ToCharLower(_a >> 8));
+            dest[9]  = TChar.CastFrom(HexConverter.ToCharLower(_a >> 4));
+            dest[10] = TChar.CastFrom(HexConverter.ToCharLower(_a));
+            dest[11] = TChar.CastFrom(',');
+            dest[12] = TChar.CastFrom('0');
+            dest[13] = TChar.CastFrom('x');
+            dest[14] = TChar.CastFrom(HexConverter.ToCharLower(_b >> 12));
+            dest[15] = TChar.CastFrom(HexConverter.ToCharLower(_b >> 8));
+            dest[16] = TChar.CastFrom(HexConverter.ToCharLower(_b >> 4));
+            dest[17] = TChar.CastFrom(HexConverter.ToCharLower(_b));
+            dest[18] = TChar.CastFrom(',');
+            dest[19] = TChar.CastFrom('0');
+            dest[20] = TChar.CastFrom('x');
+            dest[21] = TChar.CastFrom(HexConverter.ToCharLower(_c >> 12));
+            dest[22] = TChar.CastFrom(HexConverter.ToCharLower(_c >> 8));
+            dest[23] = TChar.CastFrom(HexConverter.ToCharLower(_c >> 4));
+            dest[24] = TChar.CastFrom(HexConverter.ToCharLower(_c));
+            dest[25] = TChar.CastFrom(',');
+            dest[26] = TChar.CastFrom('{');
+            WriteHex(dest, 27, _d);
+            WriteHex(dest, 32, _e);
+            WriteHex(dest, 37, _f);
+            WriteHex(dest, 42, _g);
+            WriteHex(dest, 47, _h);
+            WriteHex(dest, 52, _i);
+            WriteHex(dest, 57, _j);
+            WriteHex(dest, 62, _k, appendComma: false);
+            dest[66] = TChar.CastFrom('}');
+            dest[67] = TChar.CastFrom('}');
             charsWritten = 68;
+            return true;
 
-            fixed (TChar* guidChars = &MemoryMarshal.GetReference(destination))
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            static void WriteHex(Span<TChar> dest, int offset, int val, bool appendComma = true)
             {
-                TChar* p = guidChars;
-
-                // {0xdddddddd,0xdddd,0xdddd,{0xdd,0xdd,0xdd,0xdd,0xdd,0xdd,0xdd,0xdd}}
-                *p++ = TChar.CastFrom('{');
-                *p++ = TChar.CastFrom('0');
-                *p++ = TChar.CastFrom('x');
-                p += HexsToChars(p, _a >> 24, _a >> 16);
-                p += HexsToChars(p, _a >> 8, _a);
-                *p++ = TChar.CastFrom(',');
-                *p++ = TChar.CastFrom('0');
-                *p++ = TChar.CastFrom('x');
-                p += HexsToChars(p, _b >> 8, _b);
-                *p++ = TChar.CastFrom(',');
-                *p++ = TChar.CastFrom('0');
-                *p++ = TChar.CastFrom('x');
-                p += HexsToChars(p, _c >> 8, _c);
-                *p++ = TChar.CastFrom(',');
-                *p++ = TChar.CastFrom('{');
-                p += HexsToCharsHexOutput(p, _d, _e);
-                *p++ = TChar.CastFrom(',');
-                p += HexsToCharsHexOutput(p, _f, _g);
-                *p++ = TChar.CastFrom(',');
-                p += HexsToCharsHexOutput(p, _h, _i);
-                *p++ = TChar.CastFrom(',');
-                p += HexsToCharsHexOutput(p, _j, _k);
-                *p++ = TChar.CastFrom('}');
-                *p = TChar.CastFrom('}');
-
-                Debug.Assert(p == guidChars + charsWritten - 1);
+                dest[offset + 0] = TChar.CastFrom('0');
+                dest[offset + 1] = TChar.CastFrom('x');
+                dest[offset + 2] = TChar.CastFrom(HexConverter.ToCharLower(val >> 4));
+                dest[offset + 3] = TChar.CastFrom(HexConverter.ToCharLower(val));
+                if (appendComma)
+                {
+                    dest[offset + 4] = TChar.CastFrom(',');
+                }
             }
-
-            return true;
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]