diff --git a/SabreTools.Metadata.DatFiles.Test/DatHeaderTests.cs b/SabreTools.Metadata.DatFiles.Test/DatHeaderTests.cs
index 46c86387..e41129f5 100644
--- a/SabreTools.Metadata.DatFiles.Test/DatHeaderTests.cs
+++ b/SabreTools.Metadata.DatFiles.Test/DatHeaderTests.cs
@@ -134,12 +134,12 @@ namespace SabreTools.Metadata.DatFiles.Test
         public void CloneFormatTest()
         {
             DatHeader header = new DatHeader();
-            header.Write(DatHeader.DatFormatKey, DatFormat.Logiqx);
+            header.DatFormat = DatFormat.Logiqx;
 
             object clone = header.Clone();
             DatHeader? actual = clone as DatHeader;
             Assert.NotNull(actual);
-            Assert.Equal(DatFormat.Logiqx, actual.Read<DatFormat>(DatHeader.DatFormatKey));
+            Assert.Equal(DatFormat.Logiqx, actual.DatFormat);
         }
 
         #endregion
diff --git a/SabreTools.Metadata.DatFiles/DatHeader.cs b/SabreTools.Metadata.DatFiles/DatHeader.cs
index a1de654f..dbb570ef 100644
--- a/SabreTools.Metadata.DatFiles/DatHeader.cs
+++ b/SabreTools.Metadata.DatFiles/DatHeader.cs
@@ -17,11 +17,6 @@ namespace SabreTools.Metadata.DatFiles
     {
         #region Constants
 
-        /// <summary>
-        /// Read or write format
-        /// </summary>
-        public const string DatFormatKey = "DATFORMAT";
-
         /// <summary>
         /// External name of the DAT
         /// </summary>
@@ -77,6 +72,11 @@ namespace SabreTools.Metadata.DatFiles
             set => _internal.Date = value;
         }
 
+        /// <summary>
+        /// Read or write format
+        /// </summary>
+        public DatFormat? DatFormat { get; set; }
+
         public string? DatVersion
         {
             get => _internal.DatVersion;
@@ -299,7 +299,7 @@ namespace SabreTools.Metadata.DatFiles
         /// <summary>
         /// Clone the current header
         /// </summary>
-        public object Clone() => new DatHeader(GetInternalClone());
+        public object Clone() => new DatHeader(GetInternalClone()) { DatFormat = DatFormat };
 
         /// <summary>
         /// Clone just the format from the current header
@@ -308,7 +308,7 @@ namespace SabreTools.Metadata.DatFiles
         {
             var header = new DatHeader();
 
-            header.Write(DatFormatKey, Read<DatFormat>(DatFormatKey));
+            header.DatFormat = DatFormat;
 
             return header;
         }
diff --git a/SabreTools.Metadata.DatFiles/Formats/ArchiveDotOrg.cs b/SabreTools.Metadata.DatFiles/Formats/ArchiveDotOrg.cs
index 256037bf..f2b70574 100644
--- a/SabreTools.Metadata.DatFiles/Formats/ArchiveDotOrg.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/ArchiveDotOrg.cs
@@ -1,4 +1,4 @@
-namespace SabreTools.Metadata.DatFiles.Formats
+namespace SabreTools.Metadata.DatFiles.Formats
 {
     /// <summary>
     /// Represents a Archive.org file list
@@ -17,7 +17,7 @@
         /// <param name="datFile">Parent DatFile to copy from</param>
         public ArchiveDotOrg(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.ArchiveDotOrg);
+            Header.DatFormat = DatFormat.ArchiveDotOrg;
         }
     }
 }
diff --git a/SabreTools.Metadata.DatFiles/Formats/AttractMode.cs b/SabreTools.Metadata.DatFiles/Formats/AttractMode.cs
index 8861f40f..61578ef7 100644
--- a/SabreTools.Metadata.DatFiles/Formats/AttractMode.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/AttractMode.cs
@@ -20,7 +20,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         /// <param name="datFile">Parent DatFile to copy from</param>
         public AttractMode(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.AttractMode);
+            Header.DatFormat = DatFormat.AttractMode;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/ClrMamePro.cs b/SabreTools.Metadata.DatFiles/Formats/ClrMamePro.cs
index 46b8bf7f..e4f16d58 100644
--- a/SabreTools.Metadata.DatFiles/Formats/ClrMamePro.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/ClrMamePro.cs
@@ -39,7 +39,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         /// <param name="datFile">Parent DatFile to copy from</param>
         public ClrMamePro(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.ClrMamePro);
+            Header.DatFormat = DatFormat.ClrMamePro;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/CommaSeparatedValue.cs b/SabreTools.Metadata.DatFiles/Formats/CommaSeparatedValue.cs
index 07498563..12aa2fc1 100644
--- a/SabreTools.Metadata.DatFiles/Formats/CommaSeparatedValue.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/CommaSeparatedValue.cs
@@ -12,7 +12,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public CommaSeparatedValue(DatFile? datFile) : base(datFile)
         {
             _delim = ',';
-            Header.Write(DatHeader.DatFormatKey, DatFormat.CSV);
+            Header.DatFormat = DatFormat.CSV;
         }
     }
 }
diff --git a/SabreTools.Metadata.DatFiles/Formats/DosCenter.cs b/SabreTools.Metadata.DatFiles/Formats/DosCenter.cs
index 3a37381c..37bda622 100644
--- a/SabreTools.Metadata.DatFiles/Formats/DosCenter.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/DosCenter.cs
@@ -21,7 +21,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         /// <param name="datFile">Parent DatFile to copy from</param>
         public DosCenter(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.DOSCenter);
+            Header.DatFormat = DatFormat.DOSCenter;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/EverdriveSmdb.cs b/SabreTools.Metadata.DatFiles/Formats/EverdriveSmdb.cs
index f6efbec2..e680cc80 100644
--- a/SabreTools.Metadata.DatFiles/Formats/EverdriveSmdb.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/EverdriveSmdb.cs
@@ -21,7 +21,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         /// <param name="datFile">Parent DatFile to copy from</param>
         public EverdriveSMDB(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.EverdriveSMDB);
+            Header.DatFormat = DatFormat.EverdriveSMDB;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/Listrom.cs b/SabreTools.Metadata.DatFiles/Formats/Listrom.cs
index bfba39fa..8a5ef1cc 100644
--- a/SabreTools.Metadata.DatFiles/Formats/Listrom.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/Listrom.cs
@@ -22,7 +22,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         /// <param name="datFile">Parent DatFile to copy from</param>
         public Listrom(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.Listrom);
+            Header.DatFormat = DatFormat.Listrom;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/Listxml.cs b/SabreTools.Metadata.DatFiles/Formats/Listxml.cs
index 5af06b3a..fbdc657a 100644
--- a/SabreTools.Metadata.DatFiles/Formats/Listxml.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/Listxml.cs
@@ -216,7 +216,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         /// <param name="datFile">Parent DatFile to copy from</param>
         public Listxml(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.Listxml);
+            Header.DatFormat = DatFormat.Listxml;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/Logiqx.cs b/SabreTools.Metadata.DatFiles/Formats/Logiqx.cs
index 677968b5..dbc731cd 100644
--- a/SabreTools.Metadata.DatFiles/Formats/Logiqx.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/Logiqx.cs
@@ -253,9 +253,9 @@ namespace SabreTools.Metadata.DatFiles.Formats
         {
             _useGame = useGame;
             if (useGame)
-                Header.Write(DatHeader.DatFormatKey, DatFormat.LogiqxDeprecated);
+                Header.DatFormat = DatFormat.LogiqxDeprecated;
             else
-                Header.Write(DatHeader.DatFormatKey, DatFormat.Logiqx);
+                Header.DatFormat = DatFormat.Logiqx;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/Md2File.cs b/SabreTools.Metadata.DatFiles/Formats/Md2File.cs
index 10c5d283..b3457a79 100644
--- a/SabreTools.Metadata.DatFiles/Formats/Md2File.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/Md2File.cs
@@ -23,7 +23,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public Md2File(DatFile? datFile) : base(datFile)
         {
             _hash = HashType.MD2;
-            Header.Write(DatHeader.DatFormatKey, DatFormat.RedumpMD2);
+            Header.DatFormat = DatFormat.RedumpMD2;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/Md4File.cs b/SabreTools.Metadata.DatFiles/Formats/Md4File.cs
index 3365a09f..d1f2d030 100644
--- a/SabreTools.Metadata.DatFiles/Formats/Md4File.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/Md4File.cs
@@ -23,7 +23,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public Md4File(DatFile? datFile) : base(datFile)
         {
             _hash = HashType.MD4;
-            Header.Write(DatHeader.DatFormatKey, DatFormat.RedumpMD4);
+            Header.DatFormat = DatFormat.RedumpMD4;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/Md5File.cs b/SabreTools.Metadata.DatFiles/Formats/Md5File.cs
index c72f9502..d3b5baa4 100644
--- a/SabreTools.Metadata.DatFiles/Formats/Md5File.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/Md5File.cs
@@ -25,7 +25,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public Md5File(DatFile? datFile) : base(datFile)
         {
             _hash = HashType.MD5;
-            Header.Write(DatHeader.DatFormatKey, DatFormat.RedumpMD5);
+            Header.DatFormat = DatFormat.RedumpMD5;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/Missfile.cs b/SabreTools.Metadata.DatFiles/Formats/Missfile.cs
index ae3a250d..67152059 100644
--- a/SabreTools.Metadata.DatFiles/Formats/Missfile.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/Missfile.cs
@@ -22,7 +22,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         /// <param name="datFile">Parent DatFile to copy from</param>
         public Missfile(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.MissFile);
+            Header.DatFormat = DatFormat.MissFile;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/OfflineList.cs b/SabreTools.Metadata.DatFiles/Formats/OfflineList.cs
index 51cba1ae..3539fbfe 100644
--- a/SabreTools.Metadata.DatFiles/Formats/OfflineList.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/OfflineList.cs
@@ -21,7 +21,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         /// <param name="datFile">Parent DatFile to copy from</param>
         public OfflineList(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.OfflineList);
+            Header.DatFormat = DatFormat.OfflineList;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/OpenMSX.cs b/SabreTools.Metadata.DatFiles/Formats/OpenMSX.cs
index c062b863..1050b672 100644
--- a/SabreTools.Metadata.DatFiles/Formats/OpenMSX.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/OpenMSX.cs
@@ -60,7 +60,7 @@ The softwaredb.xml file contains information about rom mapper types
         /// <param name="datFile">Parent DatFile to copy from</param>
         public OpenMSX(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.OpenMSX);
+            Header.DatFormat = DatFormat.OpenMSX;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/RipeMD128File.cs b/SabreTools.Metadata.DatFiles/Formats/RipeMD128File.cs
index 4cadad6d..28512ed5 100644
--- a/SabreTools.Metadata.DatFiles/Formats/RipeMD128File.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/RipeMD128File.cs
@@ -23,7 +23,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public RipeMD128File(DatFile? datFile) : base(datFile)
         {
             _hash = HashType.RIPEMD128;
-            Header.Write(DatHeader.DatFormatKey, DatFormat.RedumpRIPEMD128);
+            Header.DatFormat = DatFormat.RedumpRIPEMD128;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/RipeMD160File.cs b/SabreTools.Metadata.DatFiles/Formats/RipeMD160File.cs
index 641ad2b2..4dbae14c 100644
--- a/SabreTools.Metadata.DatFiles/Formats/RipeMD160File.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/RipeMD160File.cs
@@ -23,7 +23,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public RipeMD160File(DatFile? datFile) : base(datFile)
         {
             _hash = HashType.RIPEMD160;
-            Header.Write(DatHeader.DatFormatKey, DatFormat.RedumpRIPEMD160);
+            Header.DatFormat = DatFormat.RedumpRIPEMD160;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/RomCenter.cs b/SabreTools.Metadata.DatFiles/Formats/RomCenter.cs
index 926b409f..2a73074b 100644
--- a/SabreTools.Metadata.DatFiles/Formats/RomCenter.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/RomCenter.cs
@@ -21,7 +21,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         /// <param name="datFile">Parent DatFile to copy from</param>
         public RomCenter(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.RomCenter);
+            Header.DatFormat = DatFormat.RomCenter;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/SabreJSON.cs b/SabreTools.Metadata.DatFiles/Formats/SabreJSON.cs
index 46f57435..50b39bfb 100644
--- a/SabreTools.Metadata.DatFiles/Formats/SabreJSON.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/SabreJSON.cs
@@ -32,7 +32,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         /// <param name="datFile">Parent DatFile to copy from</param>
         public SabreJSON(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.SabreJSON);
+            Header.DatFormat = DatFormat.SabreJSON;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/SabreXML.cs b/SabreTools.Metadata.DatFiles/Formats/SabreXML.cs
index 19375b9f..99c18d65 100644
--- a/SabreTools.Metadata.DatFiles/Formats/SabreXML.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/SabreXML.cs
@@ -31,7 +31,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         /// <param name="datFile">Parent DatFile to copy from</param>
         public SabreXML(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.SabreXML);
+            Header.DatFormat = DatFormat.SabreXML;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/SemicolonSeparatedValue.cs b/SabreTools.Metadata.DatFiles/Formats/SemicolonSeparatedValue.cs
index 4940b556..42c1660a 100644
--- a/SabreTools.Metadata.DatFiles/Formats/SemicolonSeparatedValue.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/SemicolonSeparatedValue.cs
@@ -12,7 +12,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public SemicolonSeparatedValue(DatFile? datFile) : base(datFile)
         {
             _delim = ';';
-            Header.Write(DatHeader.DatFormatKey, DatFormat.SSV);
+            Header.DatFormat = DatFormat.SSV;
         }
     }
 }
diff --git a/SabreTools.Metadata.DatFiles/Formats/SfvFile.cs b/SabreTools.Metadata.DatFiles/Formats/SfvFile.cs
index c2c7f122..f106c6bd 100644
--- a/SabreTools.Metadata.DatFiles/Formats/SfvFile.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/SfvFile.cs
@@ -23,7 +23,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public SfvFile(DatFile? datFile) : base(datFile)
         {
             _hash = HashType.CRC32;
-            Header.Write(DatHeader.DatFormatKey, DatFormat.RedumpSFV);
+            Header.DatFormat = DatFormat.RedumpSFV;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/Sha1File.cs b/SabreTools.Metadata.DatFiles/Formats/Sha1File.cs
index f1fe3be2..ef7ddfe2 100644
--- a/SabreTools.Metadata.DatFiles/Formats/Sha1File.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/Sha1File.cs
@@ -25,7 +25,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public Sha1File(DatFile? datFile) : base(datFile)
         {
             _hash = HashType.SHA1;
-            Header.Write(DatHeader.DatFormatKey, DatFormat.RedumpSHA1);
+            Header.DatFormat = DatFormat.RedumpSHA1;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/Sha256File.cs b/SabreTools.Metadata.DatFiles/Formats/Sha256File.cs
index 67bb2468..e24a29d3 100644
--- a/SabreTools.Metadata.DatFiles/Formats/Sha256File.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/Sha256File.cs
@@ -24,7 +24,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public Sha256File(DatFile? datFile) : base(datFile)
         {
             _hash = HashType.SHA256;
-            Header.Write(DatHeader.DatFormatKey, DatFormat.RedumpSHA256);
+            Header.DatFormat = DatFormat.RedumpSHA256;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/Sha384File.cs b/SabreTools.Metadata.DatFiles/Formats/Sha384File.cs
index 9471cdb2..2ef52335 100644
--- a/SabreTools.Metadata.DatFiles/Formats/Sha384File.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/Sha384File.cs
@@ -23,7 +23,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public Sha384File(DatFile? datFile) : base(datFile)
         {
             _hash = HashType.SHA384;
-            Header.Write(DatHeader.DatFormatKey, DatFormat.RedumpSHA384);
+            Header.DatFormat = DatFormat.RedumpSHA384;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/Sha512File.cs b/SabreTools.Metadata.DatFiles/Formats/Sha512File.cs
index cb0fdc92..81bf39a8 100644
--- a/SabreTools.Metadata.DatFiles/Formats/Sha512File.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/Sha512File.cs
@@ -23,7 +23,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public Sha512File(DatFile? datFile) : base(datFile)
         {
             _hash = HashType.SHA512;
-            Header.Write(DatHeader.DatFormatKey, DatFormat.RedumpSHA512);
+            Header.DatFormat = DatFormat.RedumpSHA512;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/SoftwareList.cs b/SabreTools.Metadata.DatFiles/Formats/SoftwareList.cs
index 40b0ec09..a0fc9f15 100644
--- a/SabreTools.Metadata.DatFiles/Formats/SoftwareList.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/SoftwareList.cs
@@ -96,7 +96,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         /// <param name="datFile">Parent DatFile to copy from</param>
         public SoftwareList(DatFile? datFile) : base(datFile)
         {
-            Header.Write(DatHeader.DatFormatKey, DatFormat.SoftwareList);
+            Header.DatFormat = DatFormat.SoftwareList;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/SpamSumFile.cs b/SabreTools.Metadata.DatFiles/Formats/SpamSumFile.cs
index b418d944..17661e36 100644
--- a/SabreTools.Metadata.DatFiles/Formats/SpamSumFile.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/SpamSumFile.cs
@@ -24,7 +24,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public SpamSumFile(DatFile? datFile) : base(datFile)
         {
             _hash = HashType.SpamSum;
-            Header.Write(DatHeader.DatFormatKey, DatFormat.RedumpSpamSum);
+            Header.DatFormat = DatFormat.RedumpSpamSum;
         }
 
         /// <inheritdoc/>
diff --git a/SabreTools.Metadata.DatFiles/Formats/TabSeparatedValue.cs b/SabreTools.Metadata.DatFiles/Formats/TabSeparatedValue.cs
index ce31ed81..369ad80b 100644
--- a/SabreTools.Metadata.DatFiles/Formats/TabSeparatedValue.cs
+++ b/SabreTools.Metadata.DatFiles/Formats/TabSeparatedValue.cs
@@ -12,7 +12,7 @@ namespace SabreTools.Metadata.DatFiles.Formats
         public TabSeparatedValue(DatFile? datFile) : base(datFile)
         {
             _delim = '\t';
-            Header.Write(DatHeader.DatFormatKey, DatFormat.TSV);
+            Header.DatFormat = DatFormat.TSV;
         }
     }
 }