diff --git a/src/ApprovalTests/TheoryTests/SerializableTheory.cs b/src/ApprovalTests/TheoryTests/SerializableTheory.cs
deleted file mode 100644
index 747708eb..00000000
--- a/src/ApprovalTests/TheoryTests/SerializableTheory.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-using System.Runtime.Serialization.Formatters.Binary;
-
-namespace ApprovalTests.TheoryTests;
-
-[Obsolete("https://github.com/dotnet/designs/blob/main/accepted/2020/better-obsoletion/binaryformatter-obsoletion.md")]
-public static class SerializableTheory
-{
-    public static void Verify(object original, Action<object, object> assertEqual)
-    {
-        var stream = new MemoryStream();
-        var formatter = new BinaryFormatter();
-        formatter.Serialize(stream, original);
-        stream.Seek(0, 0);
-        var result = formatter.Deserialize(stream);
-        assertEqual(result, original);
-    }
-}
\ No newline at end of file