diff --git a/src/Vogen/Util.cs b/src/Vogen/Util.cs
index a2ec6a7a283..b36874b6272 100644
--- a/src/Vogen/Util.cs
+++ b/src/Vogen/Util.cs
@@ -467,7 +467,7 @@ public static string GeneratePolyTypeAttributeIfAvailable(VogenKnownSymbols know
             return string.Empty;
         }
 
-        return @"    [global::PolyType.TypeShapeAttribute(Marshaler = typeof(PolyTypeMarshaler), Kind = global::PolyType.TypeShapeKind.None)]";
+        return @"    [global::PolyType.TypeShapeAttribute(Marshaler = typeof(PolyTypeMarshaler))]";
     }
 
     /// <summary>
@@ -484,12 +484,14 @@ public static string GeneratePolyTypeMarshalerIfAvailable(VogenKnownSymbols know
         var underlyingType = item.UnderlyingTypeFullName;
 
         return $@"
+        #nullable disable
         [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
-        public class PolyTypeMarshaler : global::PolyType.IMarshaler<{typeName}, {underlyingType}>
+        public sealed class PolyTypeMarshaler : global::PolyType.IMarshaler<{typeName}, {underlyingType}>
         {{
             {underlyingType} global::PolyType.IMarshaler<{typeName}, {underlyingType}>.Marshal({typeName} value) => value.Value;
             {typeName} global::PolyType.IMarshaler<{typeName}, {underlyingType}>.Unmarshal({underlyingType} value) => From(value);
-        }}";
+        }}
+        #nullable restore";
     }
 
     public static string GenerateCoverageExcludeAndGeneratedCodeAttributes() =>
diff --git a/tests/SnapshotTests/PolyType/snapshots/snap-v8.0/PolyTypeTests.PolyType_support_is_generated_with_PolyType_reference.verified.txt b/tests/SnapshotTests/PolyType/snapshots/snap-v8.0/PolyTypeTests.PolyType_support_is_generated_with_PolyType_reference.verified.txt
index 753b9c9bc80..ab28a10b23c 100644
--- a/tests/SnapshotTests/PolyType/snapshots/snap-v8.0/PolyTypeTests.PolyType_support_is_generated_with_PolyType_reference.verified.txt
+++ b/tests/SnapshotTests/PolyType/snapshots/snap-v8.0/PolyTypeTests.PolyType_support_is_generated_with_PolyType_reference.verified.txt
@@ -69,7 +69,7 @@ namespace generator
 [global::System.ComponentModel.TypeConverter(typeof(MyIdTypeConverter))]
 [global::System.Diagnostics.DebuggerTypeProxyAttribute(typeof(MyIdDebugView))]
 [global::System.Diagnostics.DebuggerDisplayAttribute("Underlying type: System.Int32, Value = { _value }")]
-[global::PolyType.TypeShapeAttribute(Marshaler = typeof(PolyTypeMarshaler), Kind = global::PolyType.TypeShapeKind.None)]
+[global::PolyType.TypeShapeAttribute(Marshaler = typeof(PolyTypeMarshaler))]
 // ReSharper disable once UnusedType.Global
 public partial struct MyId : global::System.IEquatable<MyId>, global::System.IEquatable<System.Int32>, global::System.IComparable<MyId>, global::System.IComparable, global::System.IParsable<MyId>, global::System.ISpanParsable<MyId>, global::System.IUtf8SpanParsable<MyId>, global::System.IFormattable, global::System.ISpanFormattable, global::System.IUtf8SpanFormattable
 {
@@ -735,11 +735,13 @@ private readonly global::System.Diagnostics.StackTrace _stackTrace  = null!;
         }
     }
 
+#nullable disable
     [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
-    public class PolyTypeMarshaler : global::PolyType.IMarshaler<MyId, System.Int32>
+    public sealed class PolyTypeMarshaler : global::PolyType.IMarshaler<MyId, System.Int32>
     {
         System.Int32 global::PolyType.IMarshaler<MyId, System.Int32>.Marshal(MyId value) => value.Value;
         MyId global::PolyType.IMarshaler<MyId, System.Int32>.Unmarshal(System.Int32 value) => From(value);
     }
+#nullable restore
 }
 ]
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