diff --git a/services/commtest/src/backup/backup_utils.rs b/services/commtest/src/backup/backup_utils.rs
--- a/services/commtest/src/backup/backup_utils.rs
+++ b/services/commtest/src/backup/backup_utils.rs
@@ -23,7 +23,7 @@
       Some(predefined_byte_value),
     )),
     attachments: vec![],
-    siwe_backup_msg: None,
+    siwe_backup_msg: Some("message".to_string()),
   }
 }
 
diff --git a/services/commtest/tests/backup_integration_test.rs b/services/commtest/tests/backup_integration_test.rs
--- a/services/commtest/tests/backup_integration_test.rs
+++ b/services/commtest/tests/backup_integration_test.rs
@@ -87,6 +87,7 @@
     serde_json::from_slice(&backup_info_response)?;
   assert_eq!(response.backup_id, backup_data.backup_id);
   assert_eq!(response.user_id, device_info.user_id);
+  assert_eq!(response.siwe_backup_msg, backup_data.siwe_backup_msg);
 
   let user_keys = backup_client
     .download_backup_data(&latest_backup_descriptor, RequestedData::UserKeys)
diff --git a/services/commtest/tests/backup_upload_test.rs b/services/commtest/tests/backup_upload_test.rs
--- a/services/commtest/tests/backup_upload_test.rs
+++ b/services/commtest/tests/backup_upload_test.rs
@@ -50,6 +50,7 @@
 
   assert_eq!(response.backup_id, backup_data.backup_id);
   assert_eq!(response.user_id, device_info.user_id);
+  assert_eq!(response.siwe_backup_msg, backup_data.siwe_backup_msg);
 
   let user_keys = backup_client
     .download_backup_data(&latest_backup_descriptor, RequestedData::UserKeys)
@@ -236,6 +237,7 @@
 
   assert_eq!(response.backup_id, new_user_keys.backup_id);
   assert_eq!(response.user_id, device_info.user_id);
+  assert_eq!(response.siwe_backup_msg, backup_data.siwe_backup_msg);
 
   // Test User Keys download -> should be updated
   let backup_descriptor = BackupDescriptor::BackupID {
diff --git a/shared/backup_client/src/lib.rs b/shared/backup_client/src/lib.rs
--- a/shared/backup_client/src/lib.rs
+++ b/shared/backup_client/src/lib.rs
@@ -81,11 +81,10 @@
           "user_data_hash",
           Sha256::digest(&user_data_value).encode_hex::<String>(),
         )
-        .part("user_data", Part::stream(Body::from(user_data_value)));
+        .part("user_data", Part::stream(Body::from(user_data_value)))
+        .text("attachments", attachments.join("\n"));
     }
 
-    form = form.text("attachments", attachments.join("\n"));
-
     if let Some(siwe_backup_msg_value) = siwe_backup_msg {
       form = form.text("siwe_backup_msg", siwe_backup_msg_value);
     }