diff --git a/src/backup.rs b/src/backup.rs
index 619cbb45..5707294a 100644
--- a/src/backup.rs
+++ b/src/backup.rs
@@ -121,6 +121,12 @@ pub static COMPRESSED_CHUNK_MAGIC_1_0: [u8; 8] = [191, 237, 46, 195, 108, 17, 22
 // openssl::sha::sha256(b"Proxmox Backup zstd compressed encrypted chunk v1.0")[0..8]
 pub static ENCR_COMPR_CHUNK_MAGIC_1_0: [u8; 8] = [9, 40, 53, 200, 37, 150, 90, 196];
 
+// openssl::sha::sha256(b"Proxmox Backup fixed sized chunk index v1.0")[0..8]
+pub static FIXED_SIZED_CHUNK_INDEX_1_0: [u8; 8] = [47, 127, 65, 237, 145, 253, 15, 205];
+
+// openssl::sha::sha256(b"Proxmox Backup dynamic sized chunk index v1.0")[0..8]
+pub static DYNAMIC_SIZED_CHUNK_INDEX_1_0: [u8; 8] = [28, 145, 78, 165, 25, 186, 179, 205];
+
 mod crypt_setup;
 pub use crypt_setup::*;
 
diff --git a/src/backup/dynamic_index.rs b/src/backup/dynamic_index.rs
index 1af99776..5ac633a9 100644
--- a/src/backup/dynamic_index.rs
+++ b/src/backup/dynamic_index.rs
@@ -24,13 +24,12 @@ use super::{DataChunk, DataChunkBuilder};
 #[repr(C)]
 pub struct DynamicIndexHeader {
     /// The string `PROXMOX-DIDX`
-    pub magic: [u8; 12],
-    pub version: u32,
+    pub magic: [u8; 8],
     pub uuid: [u8; 16],
     pub ctime: u64,
     /// Sha256 over the index ``SHA256(offset1||digest1||offset2||digest2||...)``
     pub index_csum: [u8; 32],
-    reserved: [u8; 4024], // overall size is one page (4096 bytes)
+    reserved: [u8; 4030], // overall size is one page (4096 bytes)
 }
 
 
@@ -80,15 +79,10 @@ impl DynamicIndexReader {
 
         let header = unsafe { &* (buffer.as_ptr() as *const DynamicIndexHeader) };
 
-        if header.magic != *b"PROXMOX-DIDX" {
+        if header.magic != super::DYNAMIC_SIZED_CHUNK_INDEX_1_0 {
             bail!("got unknown magic number for {:?}", path);
         }
 
-        let version = u32::from_le(header.version);
-        if  version != 1 {
-            bail!("got unsupported version number ({}) for {:?}", version, path);
-        }
-
         let ctime = u64::from_le(header.ctime);
 
         let rawfd = file.as_raw_fd();
@@ -429,8 +423,7 @@ impl DynamicIndexWriter {
         let mut buffer = vec::undefined(header_size);
         let header = crate::tools::map_struct_mut::<DynamicIndexHeader>(&mut buffer)?;
 
-        header.magic = *b"PROXMOX-DIDX";
-        header.version = u32::to_le(1);
+        header.magic = super::DYNAMIC_SIZED_CHUNK_INDEX_1_0;
         header.ctime = u64::to_le(ctime);
         header.uuid = *uuid.as_bytes();
 
diff --git a/src/backup/fixed_index.rs b/src/backup/fixed_index.rs
index c1f3330d..086efd56 100644
--- a/src/backup/fixed_index.rs
+++ b/src/backup/fixed_index.rs
@@ -17,16 +17,14 @@ use super::ChunkInfo;
 /// Header format definition for fixed index files (`.fidx`)
 #[repr(C)]
 pub struct FixedIndexHeader {
-    /// The string `PROXMOX-FIDX`
-    pub magic: [u8; 12],
-    pub version: u32,
+    pub magic: [u8; 8],
     pub uuid: [u8; 16],
     pub ctime: u64,
-    pub size: u64,
-    pub chunk_size: u64,
     /// Sha256 over the index ``SHA256(digest1||digest2||...)``
     pub index_csum: [u8; 32],
-    reserved: [u8; 4008], // overall size is one page (4096 bytes)
+    pub size: u64,
+    pub chunk_size: u64,
+    reserved: [u8; 4016], // overall size is one page (4096 bytes)
 }
 
 // split image into fixed size chunks
@@ -78,15 +76,10 @@ impl FixedIndexReader {
 
         let header = unsafe { &mut * (buffer.as_ptr() as *mut FixedIndexHeader) };
 
-        if header.magic != *b"PROXMOX-FIDX" {
+        if header.magic != super::FIXED_SIZED_CHUNK_INDEX_1_0 {
             bail!("got unknown magic number for {:?}", path);
         }
 
-        let version = u32::from_le(header.version);
-        if  version != 1 {
-            bail!("got unsupported version number ({})", version);
-        }
-
         let size = u64::from_le(header.size) as usize;
         let ctime = u64::from_le(header.ctime);
         let chunk_size = u64::from_le(header.chunk_size) as usize;
@@ -244,8 +237,7 @@ impl FixedIndexWriter {
         let buffer = vec![0u8; header_size];
         let header = unsafe { &mut * (buffer.as_ptr() as *mut FixedIndexHeader) };
 
-        header.magic = *b"PROXMOX-FIDX";
-        header.version = u32::to_le(1);
+        header.magic = super::FIXED_SIZED_CHUNK_INDEX_1_0;
         header.ctime = u64::to_le(ctime);
         header.size = u64::to_le(size as u64);
         header.chunk_size = u64::to_le(chunk_size as u64);