diff --git a/src/backup/catalog.rs b/src/backup/catalog.rs
index 3d68017b..4bb7c2f4 100644
--- a/src/backup/catalog.rs
+++ b/src/backup/catalog.rs
@@ -9,6 +9,7 @@ use chrono::offset::{TimeZone, Local};
 use proxmox::tools::io::ReadExt;
 
 use crate::pxar::catalog::{BackupCatalogWriter, CatalogEntryType};
+use crate::backup::file_formats::PROXMOX_CATALOG_FILE_MAGIC_1_0;
 
 enum DirEntry {
     Directory { name: Vec<u8>, start: u64 },
@@ -154,7 +155,9 @@ pub struct CatalogWriter<W> {
 impl <W: Write> CatalogWriter<W> {
 
     pub fn new(writer: W) -> Result<Self, Error> {
-        Ok(Self { writer, dirstack: vec![ DirInfo::new_rootdir() ], pos: 0 })
+        let mut me = Self { writer, dirstack: vec![ DirInfo::new_rootdir() ], pos: 0 };
+        me.write_all(&PROXMOX_CATALOG_FILE_MAGIC_1_0)?;
+        Ok(me)
     }
 
     pub fn finish(&mut self) -> Result<(), Error> {
diff --git a/src/backup/file_formats.rs b/src/backup/file_formats.rs
index ce2e2118..efc62f47 100644
--- a/src/backup/file_formats.rs
+++ b/src/backup/file_formats.rs
@@ -2,6 +2,9 @@ use endian_trait::Endian;
 
 // WARNING: PLEASE DO NOT MODIFY THOSE MAGIC VALUES
 
+// openssl::sha::sha256(b"Proxmox Backup Catalog file v1.0")[0..8]
+pub const PROXMOX_CATALOG_FILE_MAGIC_1_0: [u8; 8] = [145, 253, 96, 249, 196, 103, 88, 213];
+
 // openssl::sha::sha256(b"Proxmox Backup uncompressed blob v1.0")[0..8]
 pub const UNCOMPRESSED_BLOB_MAGIC_1_0: [u8; 8] = [66, 171, 56, 7, 190, 131, 112, 161];