diff --git a/src/backup/catalog_blob.rs b/src/backup/catalog_blob.rs
index 695261a0..478c1a1f 100644
--- a/src/backup/catalog_blob.rs
+++ b/src/backup/catalog_blob.rs
@@ -15,20 +15,21 @@ use super::{DataBlobWriter, DataBlobReader, CryptConfig};
 pub struct CatalogBlobWriter<W: Write + Seek> {
     writer: DataBlobWriter<W>,
     level: usize,
+    pos: u64,
 }
 
 impl <W: Write + Seek> CatalogBlobWriter<W> {
     pub fn new_compressed(writer: W) -> Result<Self, Error> {
         let writer = DataBlobWriter::new_compressed(writer)?;
-        Ok(Self { writer, level: 0 })
+        Ok(Self { writer, level: 0, pos: 0 })
     }
     pub fn new_signed_compressed(writer: W, config: Arc<CryptConfig>) -> Result<Self, Error> {
         let writer = DataBlobWriter::new_signed_compressed(writer, config)?;
-        Ok(Self { writer, level: 0 })
+        Ok(Self { writer, level: 0, pos: 0 })
     }
     pub fn new_encrypted_compressed(writer: W, config: Arc<CryptConfig>) -> Result<Self, Error> {
         let writer = DataBlobWriter::new_encrypted_compressed(writer, config)?;
-        Ok(Self { writer, level: 0 })
+        Ok(Self { writer, level: 0, pos: 0 })
     }
     pub fn finish(self) -> Result<W, Error> {
         self.writer.finish()
@@ -38,9 +39,9 @@ impl <W: Write + Seek> CatalogBlobWriter<W> {
 impl <W: Write + Seek> BackupCatalogWriter for CatalogBlobWriter<W> {
 
     fn start_directory(&mut self, name: &CStr) -> Result<(), Error> {
-        self.writer.write_all(&[CatalogEntryType::Directory as u8])?;
-        self.writer.write_all(name.to_bytes_with_nul())?;
-        self.writer.write_all(b"{")?;
+        self.write_all(&[CatalogEntryType::Directory as u8])?;
+        self.write_all(name.to_bytes_with_nul())?;
+        self.write_all(b"{")?;
         self.level += 1;
         Ok(())
     }
@@ -49,56 +50,63 @@ impl <W: Write + Seek> BackupCatalogWriter for CatalogBlobWriter<W> {
         if self.level == 0 {
             bail!("got unexpected end_directory level 0");
         }
-        self.writer.write_all(b"}")?;
+        self.write_all(b"}")?;
         self.level -= 1;
         Ok(())
     }
 
     fn add_file(&mut self, name: &CStr, size: u64, mtime: u64) -> Result<(), Error> {
-        self.writer.write_all(&[CatalogEntryType::File as u8])?;
-        self.writer.write_all(&size.to_le_bytes())?;
-        self.writer.write_all(&mtime.to_le_bytes())?;
-        self.writer.write_all(name.to_bytes_with_nul())?;
+        self.write_all(&[CatalogEntryType::File as u8])?;
+        self.write_all(&size.to_le_bytes())?;
+        self.write_all(&mtime.to_le_bytes())?;
+        self.write_all(name.to_bytes_with_nul())?;
         Ok(())
     }
 
     fn add_symlink(&mut self, name: &CStr) -> Result<(), Error> {
-        self.writer.write_all(&[CatalogEntryType::Symlink as u8])?;
-        self.writer.write_all(name.to_bytes_with_nul())?;
+        self.write_all(&[CatalogEntryType::Symlink as u8])?;
+        self.write_all(name.to_bytes_with_nul())?;
         Ok(())
     }
 
     fn add_hardlink(&mut self, name: &CStr) -> Result<(), Error> {
-        self.writer.write_all(&[CatalogEntryType::Hardlink as u8])?;
-        self.writer.write_all(name.to_bytes_with_nul())?;
+        self.write_all(&[CatalogEntryType::Hardlink as u8])?;
+        self.write_all(name.to_bytes_with_nul())?;
         Ok(())
     }
 
     fn add_block_device(&mut self, name: &CStr) -> Result<(), Error> {
-        self.writer.write_all(&[CatalogEntryType::BlockDevice as u8])?;
-        self.writer.write_all(name.to_bytes_with_nul())?;
+        self.write_all(&[CatalogEntryType::BlockDevice as u8])?;
+        self.write_all(name.to_bytes_with_nul())?;
         Ok(())
     }
 
     fn add_char_device(&mut self, name: &CStr) -> Result<(), Error> {
-        self.writer.write_all(&[CatalogEntryType::CharDevice as u8])?;
-        self.writer.write_all(name.to_bytes_with_nul())?;
+        self.write_all(&[CatalogEntryType::CharDevice as u8])?;
+        self.write_all(name.to_bytes_with_nul())?;
         Ok(())
     }
 
     fn add_fifo(&mut self, name: &CStr) -> Result<(), Error> {
-        self.writer.write_all(&[CatalogEntryType::Fifo as u8])?;
-        self.writer.write_all(name.to_bytes_with_nul())?;
+        self.write_all(&[CatalogEntryType::Fifo as u8])?;
+        self.write_all(name.to_bytes_with_nul())?;
         Ok(())
     }
 
     fn add_socket(&mut self, name: &CStr) -> Result<(), Error> {
-        self.writer.write_all(&[CatalogEntryType::Socket as u8])?;
-        self.writer.write_all(name.to_bytes_with_nul())?;
+        self.write_all(&[CatalogEntryType::Socket as u8])?;
+        self.write_all(name.to_bytes_with_nul())?;
         Ok(())
     }
 }
 
+impl<W: Write + Seek> CatalogBlobWriter<W> {
+    fn write_all(&mut self, data: &[u8]) -> Result<(), Error> {
+        self.writer.write_all(data)?;
+        self.pos += u64::try_from(data.len())?;
+        Ok(())
+    }
+}
 
 pub struct CatalogBlobReader<R: Read + BufRead> {
     reader: BufReader<DataBlobReader<R>>,