diff --git a/mutannot.fsx b/mutannot.fsx
index 93c2c13..821447f 100755
--- a/mutannot.fsx
+++ b/mutannot.fsx
@@ -224,26 +224,6 @@ let tempRoot = Path.Combine(Path.GetTempPath(), $"fscheck-mutants.{Guid.NewGuid(
 let worktreePath = Path.Combine(tempRoot, "worktree")
 let patchPath = Path.Combine(tempRoot, "current.patch")
 
-let splitNullSeparated (text: string) =
-    text.Split('\000', StringSplitOptions.RemoveEmptyEntries)
-    |> Array.toList
-
-let repoRelativePath (path: string) =
-    path.Replace('/', Path.DirectorySeparatorChar)
-
-let listUntrackedFiles () =
-    let exitCode, stdout, stderr = captureProcess repoRoot "git" [ "ls-files"; "--others"; "--exclude-standard"; "-z" ]
-    if exitCode <> 0 then fail stderr
-    splitNullSeparated stdout
-
-let copyFileIntoWorktree (relativePath: string) =
-    let sourcePath = Path.Combine(repoRoot, repoRelativePath relativePath)
-    let destinationPath = Path.Combine(worktreePath, repoRelativePath relativePath)
-    let destinationDir = Path.GetDirectoryName destinationPath
-    if not (String.IsNullOrEmpty destinationDir) then
-        Directory.CreateDirectory(destinationDir) |> ignore
-    File.Copy(sourcePath, destinationPath, true)
-
 let cleanup () =
     if Directory.Exists worktreePath then
         let _ = captureProcess repoRoot "git" [ "worktree"; "remove"; "--force"; worktreePath ]
@@ -253,7 +233,6 @@ let cleanup () =
 
 let createWorktree () =
     Directory.CreateDirectory(tempRoot) |> ignore
-    let untrackedFiles = listUntrackedFiles ()
     let exitCode, diffText, stderr = captureProcess repoRoot "git" [ "diff"; "--binary"; "HEAD" ]
     if exitCode <> 0 then fail stderr
     File.WriteAllText(patchPath, diffText)
@@ -269,14 +248,7 @@ let createWorktree () =
         let exitCode4, _, stderr4 = captureProcess worktreePath "git" [ "apply"; patchPath ]
         if exitCode4 <> 0 then fail stderr4
 
-    for relativePath in untrackedFiles do
-        copyFileIntoWorktree relativePath
-
-let fullyQualifiedTestName mutation =
-    let declaringType = mutation.DeclaringType.Replace('+', '.')
-    $"{declaringType}.{mutation.TestName}"
-
-let testFilter mutation = $"FullyQualifiedName={fullyQualifiedTestName mutation}"
+let testFilter mutation = $"FullyQualifiedName~{mutation.TestName}"
 
 let runMutation (mutation: MutationCase) =
     let targetFile = Path.Combine(worktreePath, mutation.File.Replace('/', Path.DirectorySeparatorChar))