diff --git a/src/backend/decrypt.rs b/src/backend/decrypt.rs
index ebb2a7e..0c01410 100644
--- a/src/backend/decrypt.rs
+++ b/src/backend/decrypt.rs
@@ -1,4 +1,5 @@
 use std::fs::File;
+use std::num::NonZeroU32;
 
 use anyhow::{bail, Result};
 use async_trait::async_trait;
@@ -23,6 +24,7 @@ pub trait DecryptReadBackend: ReadBackend {
         cacheable: bool,
         offset: u32,
         length: u32,
+        uncompressed_length: Option<NonZeroU32>,
     ) -> Result<Vec<u8>>;
 
     async fn get_file<F: RepoFile>(&self, id: &Id) -> Result<F> {
@@ -176,13 +178,21 @@ impl<R: ReadBackend, C: CryptoKey> DecryptReadBackend for DecryptBackend<R, C> {
         cacheable: bool,
         offset: u32,
         length: u32,
+        uncompressed_length: Option<NonZeroU32>,
     ) -> Result<Vec<u8>> {
-        Ok(self.key.decrypt_data(
+        let mut data = self.key.decrypt_data(
             &self
                 .backend
                 .read_partial(tpe, id, cacheable, offset, length)
                 .await?,
-        )?)
+        )?;
+        if let Some(length) = uncompressed_length {
+            data = decode_all(&*data).unwrap();
+            if data.len() != length.get() as usize {
+                bail!("length of uncompressed data does not match!");
+            }
+        }
+        Ok(data)
     }
 }
 
diff --git a/src/backend/dry_run.rs b/src/backend/dry_run.rs
index 0d0cc83..1371fe6 100644
--- a/src/backend/dry_run.rs
+++ b/src/backend/dry_run.rs
@@ -1,4 +1,5 @@
 use std::fs::File;
+use std::num::NonZeroU32;
 
 use anyhow::Result;
 use async_trait::async_trait;
@@ -32,9 +33,10 @@ impl<BE: DecryptFullBackend> DecryptReadBackend for DryRunBackend<BE> {
         cacheable: bool,
         offset: u32,
         length: u32,
+        uncompressed_length: Option<NonZeroU32>,
     ) -> Result<Vec<u8>> {
         self.be
-            .read_encrypted_partial(tpe, id, cacheable, offset, length)
+            .read_encrypted_partial(tpe, id, cacheable, offset, length, uncompressed_length)
             .await
     }
 }
diff --git a/src/blob/packer.rs b/src/blob/packer.rs
index 90b7b33..65eb2bb 100644
--- a/src/blob/packer.rs
+++ b/src/blob/packer.rs
@@ -359,6 +359,7 @@ impl<BE: DecryptFullBackend> Repacker<BE> {
                 blob.tpe.is_cacheable(),
                 blob.offset,
                 blob.length,
+                blob.uncompressed_length,
             )
             .await?;
         self.packer
diff --git a/src/commands/restore.rs b/src/commands/restore.rs
index 317884d..ca4ffd4 100644
--- a/src/commands/restore.rs
+++ b/src/commands/restore.rs
@@ -8,7 +8,6 @@ use derive_getters::Dissolve;
 use futures::{stream::FuturesUnordered, TryStreamExt};
 use tokio::spawn;
 use vlog::*;
-use zstd::decode_all;
 
 use super::{progress_bytes, progress_counter};
 use crate::backend::{DecryptReadBackend, FileType, LocalBackend};
@@ -131,17 +130,17 @@ async fn restore_contents(
             stream.push(spawn(async move {
                 // read pack at blob_offset with length blob_length
                 let data = be
-                    .read_encrypted_partial(FileType::Pack, &pack, false, bl.offset, bl.length)
+                    .read_encrypted_partial(
+                        FileType::Pack,
+                        &pack,
+                        false,
+                        bl.offset,
+                        bl.length,
+                        bl.uncompressed_length,
+                    )
                     .await
                     .unwrap();
 
-                let data = match bl.uncompressed_length.is_some() {
-                    false => data,
-                    true => decode_all(&*data).unwrap(),
-                };
-
-                // TODO: check length of uncomressed data
-
                 if !dry_run {
                     // save into needed files in parallel
                     for (name, start) in name_dests {
diff --git a/src/index/mod.rs b/src/index/mod.rs
index a01780a..ba822b7 100644
--- a/src/index/mod.rs
+++ b/src/index/mod.rs
@@ -9,7 +9,6 @@ use derive_more::Constructor;
 use futures::StreamExt;
 use indicatif::ProgressBar;
 use vlog::*;
-use zstd::decode_all;
 
 use crate::backend::{DecryptReadBackend, FileType};
 use crate::blob::BlobType;
@@ -51,12 +50,10 @@ impl IndexEntry {
                 self.blob_type.is_cacheable(),
                 self.offset,
                 self.length,
+                self.uncompressed_length,
             )
             .await?;
-        Ok(match self.uncompressed_length {
-            None => data,
-            Some(_) => decode_all(&*data)?,
-        })
+        Ok(data)
     }
 
     pub fn data_length(&self) -> u32 {