diff --git a/Files/Logiqx.Serializer.cs b/Files/Logiqx.Serializer.cs
index 3cfa233e..b15b6839 100644
--- a/Files/Logiqx.Serializer.cs
+++ b/Files/Logiqx.Serializer.cs
@@ -5,7 +5,7 @@ namespace SabreTools.Serialization.Files
     public partial class Logiqx : XmlFile<Datafile>
     {
         /// <inheritdoc cref="Serialize(Datafile, string, string?, string?, string?, string?)" />
-        public bool SerializeToFileWithDocType(Datafile obj, string path)
+        public bool SerializeToFileWithDocType(Datafile? obj, string path)
             => Serialize(obj, path, Serialization.Logiqx.DocTypeName, Serialization.Logiqx.DocTypePubId, Serialization.Logiqx.DocTypeSysId, Serialization.Logiqx.DocTypeSysId);
     }
 }
\ No newline at end of file
diff --git a/Files/OpenMSX.Serializer.cs b/Files/OpenMSX.Serializer.cs
index 44c6ec66..320138c8 100644
--- a/Files/OpenMSX.Serializer.cs
+++ b/Files/OpenMSX.Serializer.cs
@@ -5,7 +5,7 @@ namespace SabreTools.Serialization.Files
     public partial class OpenMSX : XmlFile<SoftwareDb>
     {
         /// <inheritdoc cref="Serialize(SoftwareDb, string, string?, string?, string?, string?)" />
-        public bool SerializeToFileWithDocType(SoftwareDb obj, string path)
+        public bool SerializeToFileWithDocType(SoftwareDb? obj, string path)
             => Serialize(obj, path, Serialization.OpenMSX.DocTypeName, Serialization.OpenMSX.DocTypePubId, Serialization.OpenMSX.DocTypeSysId, Serialization.OpenMSX.DocTypeSysId);
     }
 }
\ No newline at end of file
diff --git a/Files/SoftwareList.Serializer.cs b/Files/SoftwareList.Serializer.cs
index 3bba5747..38efaade 100644
--- a/Files/SoftwareList.Serializer.cs
+++ b/Files/SoftwareList.Serializer.cs
@@ -3,7 +3,7 @@ namespace SabreTools.Serialization.Files
     public partial class SoftwareList : XmlFile<Models.SoftwareList.SoftwareList>
     {
         /// <inheritdoc cref="SerializeToFile(Models.SoftwareList.SoftwareList, string, string?, string?, string?, string?)" />
-        public bool SerializeToFileWithDocType(Models.SoftwareList.SoftwareList obj, string path)
+        public bool SerializeToFileWithDocType(Models.SoftwareList.SoftwareList? obj, string path)
             => Serialize(obj, path, Serialization.SoftawreList.DocTypeName, Serialization.SoftawreList.DocTypePubId, Serialization.SoftawreList.DocTypeSysId, Serialization.SoftawreList.DocTypeSysId);
     }
 }
\ No newline at end of file