diff --git a/SabreTools.Models/Compression/Deflate/Constants.cs b/SabreTools.Models/Compression/Deflate/Constants.cs
new file mode 100644
index 0000000..a41e679
--- /dev/null
+++ b/SabreTools.Models/Compression/Deflate/Constants.cs
@@ -0,0 +1,136 @@
+namespace SabreTools.Models.Compression.Deflate
+{
+    /// <see href="https://www.rfc-editor.org/rfc/rfc1951"/>
+    public static class Constants
+    {
+        /// <summary>
+        /// Bits in base literal/length lookup table
+        /// </summary>
+        public const int ZIPLBITS = 9;
+
+        /// <summary>
+        /// Bits in base distance lookup table
+        /// </summary>
+        public const int ZIPDBITS = 6;
+
+        /// <summary>
+        /// Maximum bit length of any code
+        /// </summary>
+        public const int ZIPBMAX = 16;
+
+        /// <summary>
+        /// Maximum number of codes in any set
+        /// </summary>
+        public const int ZIPN_MAX = 288;
+
+        #region Fixed Huffman Codes
+
+        /// <summary>
+        /// Fixed Huffman code lengths for the literal / length alphabet
+        /// </summary>
+        public static readonly uint[] FixedLiteralLengths =
+        [
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            8, 8, 8, 8, 8, 8, 8, 8,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            9, 9, 9, 9, 9, 9, 9, 9,
+            7, 7, 7, 7, 7, 7, 7, 7,
+            7, 7, 7, 7, 7, 7, 7, 7,
+            7, 7, 7, 7, 7, 7, 7, 7,
+            8, 8, 8, 8, 8, 8, 8, 8,
+        ];
+
+        /// <summary>
+        /// Fixed Huffman distance codes for the literal / length alphabet
+        /// </summary>
+        public static readonly uint[] FixedDistanceCodes =
+        [
+            5, 5, 5, 5, 5, 5, 5, 5,
+            5, 5, 5, 5, 5, 5, 5, 5,
+            5, 5, 5, 5, 5, 5, 5, 5,
+            5, 5, 5, 5, 5, 5,
+        ];
+
+        #endregion
+
+        #region Literal and Length Alphabets
+
+        /// <summary>
+        /// Extra bits for distance codes
+        /// </summary>
+        public static readonly ushort[] DistanceExtraBits =
+        [
+            0, 0, 0, 0, 1, 1, 2, 2, 3, 3,
+            4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
+            9, 9, 10, 10, 11, 11, 12, 12, 13, 13
+        ];
+
+        /// <summary>
+        /// Copy offsets for distance codes 0..29
+        /// </summary>
+        public static readonly ushort[] DistanceOffsets =
+        [
+            1, 2, 3, 4, 5, 7, 9, 13, 17, 25,
+            33, 49, 65, 97, 129, 193, 257, 385, 513, 769,
+            1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577
+        ];
+
+        /// <summary>
+        /// Extra bits for literal codes 257..285
+        /// </summary>
+        public static readonly ushort[] LiteralExtraBits =
+        [
+            0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
+            1, 1, 2, 2, 2, 2, 3, 3, 3, 3,
+            4, 4, 4, 4, 5, 5, 5, 5, 0,
+        ];
+
+        /// <summary>
+        /// Copy lengths for literal codes 257..285
+        /// </summary>
+        public static readonly ushort[] LiteralLengths =
+        [
+            3, 4, 5, 6, 7, 8, 9, 10, 11, 13,
+            15, 17, 19, 23, 27, 31, 35, 43, 51, 59,
+            67, 83, 99, 115, 131, 163, 195, 227, 258,
+        ];
+
+        /// <summary>
+        /// Order of the bit length code lengths
+        /// </summary>
+        public static readonly byte[] BitLengthOrder =
+        [
+            16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
+        ];
+
+        #endregion
+    }
+}
\ No newline at end of file
diff --git a/SabreTools.Models/Compression/Deflate/FixedCompressedDataHeader.cs b/SabreTools.Models/Compression/Deflate/FixedCompressedDataHeader.cs
index d3e8d78..39c3b8e 100644
--- a/SabreTools.Models/Compression/Deflate/FixedCompressedDataHeader.cs
+++ b/SabreTools.Models/Compression/Deflate/FixedCompressedDataHeader.cs
@@ -1,5 +1,3 @@
-using System;
-
 namespace SabreTools.Models.Compression.Deflate
 {
     /// <summary>
@@ -14,80 +12,12 @@ namespace SabreTools.Models.Compression.Deflate
         /// <summary>
         /// Huffman code lengths for the literal / length alphabet
         /// </summary>
-        public override uint[]? LiteralLengths
-        {
-            get
-            {
-                // If we have cached lengths, use those
-                if (_literalLengths != null)
-                    return _literalLengths;
-
-                // Otherwise, build it from scratch
-                _literalLengths = new uint[288];
-
-                // Literal Value 0 - 143, 8 bits
-                for (int i = 0; i < 144; i++)
-                    _literalLengths[i] = 8;
-
-                // Literal Value 144 - 255, 9 bits
-                for (int i = 144; i < 256; i++)
-                    _literalLengths[i] = 9;
-
-                // Literal Value 256 - 279, 7 bits
-                for (int i = 256; i < 280; i++)
-                    _literalLengths[i] = 7;
-
-                // Literal Value 280 - 287, 8 bits
-                for (int i = 280; i < 288; i++)
-                    _literalLengths[i] = 8;
-
-                return _literalLengths;
-            }
-            set
-            {
-                throw new FieldAccessException();
-            }
-        }
+        public override uint[]? LiteralLengths => Constants.FixedLiteralLengths;
 
         /// <summary>
         /// Huffman distance codes for the literal / length alphabet
         /// </summary>
-        public override uint[]? DistanceCodes
-        {
-            get
-            {
-                // If we have cached distances, use those
-                if (_distanceCodes != null)
-                    return _distanceCodes;
-
-                // Otherwise, build it from scratch
-                _distanceCodes = new uint[30];
-
-                // Fixed length, 5 bits
-                for (int i = 0; i < 30; i++)
-                    _distanceCodes[i] = 5;
-
-                return _distanceCodes;
-            }
-            set
-            {
-                throw new FieldAccessException();
-            }
-        }
-
-        #endregion
-
-        #region Instance Variables
-
-        /// <summary>
-        /// Huffman code lengths for the literal / length alphabet
-        /// </summary>
-        private uint[]? _literalLengths = null;
-
-        /// <summary>
-        /// Huffman distance codes for the literal / length alphabet
-        /// </summary>
-        private uint[]? _distanceCodes = null;
+        public override uint[]? DistanceCodes => Constants.FixedDistanceCodes;
 
         #endregion
     }
diff --git a/SabreTools.Models/Compression/MSZIP/Constants.cs b/SabreTools.Models/Compression/MSZIP/Constants.cs
index a1bb475..537dc9f 100644
--- a/SabreTools.Models/Compression/MSZIP/Constants.cs
+++ b/SabreTools.Models/Compression/MSZIP/Constants.cs
@@ -8,73 +8,6 @@ namespace SabreTools.Models.Compression.MSZIP
         /// </summary>
         public const ushort ZIPWSIZE = 0x8000;
 
-        /// <summary>
-        /// Bits in base literal/length lookup table
-        /// </summary>
-        public const int ZIPLBITS = 9;
-
-        /// <summary>
-        /// Bits in base distance lookup table
-        /// </summary>
-        public const int ZIPDBITS = 6;
-
-        /// <summary>
-        /// Maximum bit length of any code
-        /// </summary>
-        public const int ZIPBMAX = 16;
-
-        /// <summary>
-        /// Maximum number of codes in any set
-        /// </summary>
-        public const int ZIPN_MAX = 288;
-
-        #region THOSE_ZIP_CONSTS
-
-        /// <summary>
-        /// Order of the bit length code lengths
-        /// </summary>
-        public static readonly byte[] BitLengthOrder =
-        [
-            16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
-        ];
-
-        /// <summary>
-        /// Copy lengths for literal codes 257..285
-        /// </summary>
-        public static readonly ushort[] CopyLengths =
-        [
-            3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 35, 43, 51,
-            59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0
-        ];
-
-        /// <summary>
-        /// Extra bits for literal codes 257..285
-        /// </summary>
-        /// <remarks>99 == invalid</remarks>
-        public static readonly ushort[] LiteralExtraBits =
-        [
-            0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4,
-            4, 5, 5, 5, 5, 0, 99, 99
-        ];
-
-        /// <summary>
-        /// Copy offsets for distance codes 0..29
-        /// </summary>
-        public static readonly ushort[] CopyOffsets =
-        [
-            1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385,
-            513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577
-        ];
-
-        /// <summary>
-        /// Extra bits for distance codes
-        /// </summary>
-        public static readonly ushort[] DistanceExtraBits =
-        [
-            0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10,
-            10, 11, 11, 12, 12, 13, 13
-        ];
-
         /// <summary>
         /// And'ing with Zipmask[n] masks the lower n bits
         /// </summary>
@@ -83,7 +16,5 @@ namespace SabreTools.Models.Compression.MSZIP
             0x0000, 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
             0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
         ];
-
-        #endregion
     }
 }
\ No newline at end of file