diff --git a/src/index.rs b/src/index.rs
index 0b7d5e2..17854df 100644
--- a/src/index.rs
+++ b/src/index.rs
@@ -5,12 +5,16 @@ use serde::{Deserialize, Serialize};
 use crate::error::BakareError;
 use crate::repository_item::RepositoryItem;
 use std::fs::File;
+use std::ops::Deref;
+
+#[derive(Clone, Debug, PartialOrd, PartialEq, Ord, Eq, Serialize, Deserialize)]
+pub struct ItemVersion(Box<[u8]>);
 
 #[derive(Clone, Debug, PartialOrd, PartialEq, Ord, Eq, Serialize, Deserialize)]
 pub struct IndexItem {
     relative_path: String,
     original_source_path: String,
-    version: Box<[u8]>,
+    version: ItemVersion,
 }
 
 #[derive(Serialize, Deserialize)]
@@ -20,6 +24,26 @@ pub struct Index {
     repository_path: String,
 }
 
+impl AsRef<[u8]> for ItemVersion {
+    fn as_ref(&self) -> &[u8] {
+        &self.0
+    }
+}
+
+impl Deref for ItemVersion {
+    type Target = [u8];
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl From<&[u8]> for ItemVersion {
+    fn from(a: &[u8]) -> Self {
+        ItemVersion(Box::from(a))
+    }
+}
+
 impl Index {
     pub fn new(repository_path: &Path) -> Self {
         Index {
@@ -81,7 +105,7 @@ impl From<RepositoryItem> for IndexItem {
         IndexItem {
             relative_path: i.relative_path().to_string_lossy().to_string(),
             original_source_path: i.original_source_path().to_string_lossy().to_string(),
-            version: i.version(),
+            version: i.version().clone(),
         }
     }
 }
diff --git a/src/repository.rs b/src/repository.rs
index b191a4d..31e4fc7 100644
--- a/src/repository.rs
+++ b/src/repository.rs
@@ -2,7 +2,7 @@ use std::path::Path;
 use std::{fs, io};
 
 use crate::error::BakareError;
-use crate::index::{Index, IndexIterator};
+use crate::index::{Index, IndexIterator, ItemVersion};
 use crate::repository_item::RepositoryItem;
 use sha2::Digest;
 use sha2::Sha512;
@@ -82,15 +82,14 @@ impl<'a> Repository<'a> {
         Ok(())
     }
 
-    fn calculate_version(source_path: &Path) -> Result<Box<[u8]>, BakareError> {
+    fn calculate_version(source_path: &Path) -> Result<ItemVersion, BakareError> {
         let source_file = File::open(source_path)?;
         let mut reader = BufReader::new(source_file);
         let mut hasher = Sha512::new();
 
         io::copy(&mut reader, &mut hasher)?;
 
-        let version = hasher.result();
-        Ok(Box::from(version.as_slice()))
+        Ok(hasher.result().as_slice().into())
     }
 
     pub fn item_by_source_path(&self, path: &Path) -> Result<Option<RepositoryItem>, BakareError> {
diff --git a/src/repository_item.rs b/src/repository_item.rs
index 60e2a77..83cd3cc 100644
--- a/src/repository_item.rs
+++ b/src/repository_item.rs
@@ -1,4 +1,5 @@
 use crate::error::BakareError;
+use crate::index::ItemVersion;
 use std::fmt::{Display, Formatter};
 use std::path::Path;
 use std::{fmt, fs};
@@ -8,11 +9,11 @@ pub struct RepositoryItem {
     relative_path: Box<Path>,
     absolute_path: Box<Path>,
     original_source_path: Box<Path>,
-    version: Box<[u8]>,
+    version: ItemVersion,
 }
 
 impl RepositoryItem {
-    pub fn from(original_source_path: &Path, absolute_path: &Path, relative_path: &Path, version: Box<[u8]>) -> Self {
+    pub fn from(original_source_path: &Path, absolute_path: &Path, relative_path: &Path, version: ItemVersion) -> Self {
         RepositoryItem {
             relative_path: Box::from(relative_path),
             absolute_path: Box::from(absolute_path),
@@ -50,8 +51,8 @@ impl RepositoryItem {
         &self.original_source_path
     }
 
-    pub fn version(&self) -> Box<[u8]> {
-        self.version.clone()
+    pub fn version(&self) -> &ItemVersion {
+        &self.version
     }
 }
 
diff --git a/src/restore.rs b/src/restore.rs
index a582e31..346a966 100644
--- a/src/restore.rs
+++ b/src/restore.rs
@@ -1,6 +1,7 @@
 use std::path::Path;
 
 use crate::error::BakareError;
+use crate::index::ItemVersion;
 use crate::repository::Repository;
 use crate::repository_item::RepositoryItem;
 
@@ -29,4 +30,9 @@ impl<'a> Engine<'a> {
         item.save(self.target_path)?;
         Ok(())
     }
+
+    pub fn restore_as_of_version(&self, item: &RepositoryItem, version: &ItemVersion) -> Result<(), BakareError> {
+        println!("restoring {}", item);
+        Ok(())
+    }
 }
diff --git a/tests/system_tests.rs b/tests/system_tests.rs
index 37dd10b..7a8f99f 100644
--- a/tests/system_tests.rs
+++ b/tests/system_tests.rs
@@ -75,7 +75,7 @@ fn restore_older_version_of_file() -> Result<(), BakareError> {
     let item = reading_repository.item_by_source_path(&file_path)?;
     assert!(item.is_some());
     let item = item.unwrap();
-    let _old_version = item.version();
+    let old_version = item.version();
 
     {
         let new_contents = "totally new contents";
@@ -87,8 +87,8 @@ fn restore_older_version_of_file() -> Result<(), BakareError> {
 
     let restore_repository = Repository::open(repository_path.as_path())?;
     let restore_target = tempdir()?;
-    let _restore_engine = restore::Engine::new(&restore_repository, &restore_target.path())?;
-    //restore_engine.restore_as_of_version(&item, old_version)?;
+    let restore_engine = restore::Engine::new(&restore_repository, &restore_target.path())?;
+    restore_engine.restore_as_of_version(&item, old_version)?;
 
     assert_target_file_contents(restore_target.path(), relative_path_text, old_contents)
 }
@@ -161,3 +161,5 @@ fn get_sorted_files_recursively(path: &Path) -> Result<Vec<Box<Path>>, BakareErr
 }
 // TODO: restore latest version by default
 // TODO: deduplicate data
+// TODO: test that index is stored separately from data
+// TODO: index corruption