diff --git a/benchmark-new/benchmark_repository/examples/test.rs b/benchmark-new/benchmark_repository/examples/test.rs
index 1cd10335e..22621e5c2 100644
--- a/benchmark-new/benchmark_repository/examples/test.rs
+++ b/benchmark-new/benchmark_repository/examples/test.rs
@@ -10,5 +10,5 @@ fn main()
 	pretty_env_logger::init();
 
 	let benchmark_repository = BenchmarkRepository::new("git@git.luehne.de:patrick/tplp-planning-benchmark.git", Path::new("storage"), "git", "Potassco Bot", "bot@potassco.org");
-	benchmark_repository.commit_file(Path::new("/tmp/test"), Path::new("test-result/test"), "test-results");
+	benchmark_repository.commit_file(Path::new("/tmp/test"), Path::new("test-new/fourth"), "test-results");
 }
diff --git a/benchmark-new/benchmark_repository/src/lib.rs b/benchmark-new/benchmark_repository/src/lib.rs
index a467887d4..dc1c9cbfa 100644
--- a/benchmark-new/benchmark_repository/src/lib.rs
+++ b/benchmark-new/benchmark_repository/src/lib.rs
@@ -4,7 +4,7 @@ extern crate pretty_env_logger;
 extern crate log;
 extern crate indicatif;
 
-use git2::{Cred, Error, FetchOptions, Progress, PushOptions, RemoteCallbacks, ResetType, Repository, Signature, TreeBuilder};
+use git2::{Cred, Error, FetchOptions, Index, IndexEntry, IndexTime, Progress, PushOptions, RemoteCallbacks, ResetType, Repository, Signature, TreeBuilder};
 use git2::build::{CheckoutBuilder, RepoBuilder};
 use std::fs::read;
 use std::path::Path;
@@ -202,15 +202,8 @@ impl BenchmarkRepository
 		benchmark_repository
 	}
 
-	pub fn commit_file(&self, file_path: &Path, result_file_path: &Path, branch_name: &str)
+	pub fn read_file_as_index_entry(&self, file_path: &Path, result_file_path: &Path) -> IndexEntry
 	{
-		let reference_name = format!("refs/remotes/origin/{}", branch_name);
-		let reference = match self.repository.find_reference(&reference_name)
-		{
-			Ok(value) => value,
-			Err(error) => panic!("Could not find reference “{}”: {}", reference_name, error),
-		};
-
 		// create a new blob with the file contents
 		let object_id = match self.repository.blob_path(file_path)
 		{
@@ -220,24 +213,61 @@ impl BenchmarkRepository
 
 		info!("Created object “{}” from “{}”", object_id, file_path.display());
 
+		IndexEntry
+		{
+			ctime: IndexTime::new(0, 0),
+			mtime: IndexTime::new(0, 0),
+			dev: 0,
+			ino: 0,
+			mode: 0o100644,
+			uid: 0,
+			gid: 0,
+			file_size: 0,
+			id: object_id,
+			flags: 0,
+			flags_extended: 0,
+			path: result_file_path.to_string_lossy().as_bytes().to_owned(),
+		}
+	}
+
+	pub fn commit_file(&self, file_path: &Path, result_file_path: &Path, branch_name: &str)
+	{
+		let reference_name = format!("refs/remotes/origin/{}", branch_name);
+		let reference = match self.repository.find_reference(&reference_name)
+		{
+			Ok(value) => value,
+			Err(error) => panic!("Could not find reference “{}”: {}", reference_name, error),
+		};
+
 		let parent_tree = match reference.peel_to_tree()
 		{
 			Ok(value) => value,
 			Err(error) => panic!("Could not peel reference to tree: {}", error),
 		};
 
-		let mut tree_builder = match self.repository.treebuilder(Some(&parent_tree))
-		{
-			Ok(tree_builder) => tree_builder,
-			Err(error) => panic!("Could not obtain tree builder: {}", error),
-		};
-
-		tree_builder.insert("foobartest/test2/foobar", object_id, 0o100644);
-
-		let tree_object_id = match tree_builder.write()
+		let mut index = match Index::new()
 		{
 			Ok(value) => value,
-			Err(error) => panic!("Could not write tree: {}", error),
+			Err(error) => panic!("Could not create index: {}", error),
+		};
+
+		match index.read_tree(&parent_tree)
+		{
+			Ok(value) => value,
+			Err(error) => panic!("Could not read parent tree into index: {}", error),
+		};
+
+		let index_entry = self.read_file_as_index_entry(file_path, result_file_path);
+
+		if let Err(error) = index.add(&index_entry)
+		{
+			panic!("Could not add index entry: {}", error);
+		}
+
+		let tree_object_id = match index.write_tree_to(&self.repository)
+		{
+			Ok(value) => value,
+			Err(error) => panic!("Could not write index to tree: {}", error),
 		};
 
 		let tree = match self.repository.find_tree(tree_object_id)