diff --git a/src/api2/backup.rs b/src/api2/backup.rs
index 13463716..74bd5fb8 100644
--- a/src/api2/backup.rs
+++ b/src/api2/backup.rs
@@ -86,6 +86,9 @@ fn upgrade_to_backup_protocol(
         if backup_dir.backup_time() <= last.backup_dir.backup_time() {
             bail!("backup timestamp is older than last backup.");
         }
+        // fixme: abort if last backup is still running - howto test?
+        // Idea: write upid into a file inside snapshot dir. then test if
+        // it is still running here.
     }
 
     let (path, is_new) = datastore.create_backup_dir(&backup_dir)?;
diff --git a/src/backup/backup_info.rs b/src/backup/backup_info.rs
index 78858dd6..8562635d 100644
--- a/src/backup/backup_info.rs
+++ b/src/backup/backup_info.rs
@@ -138,18 +138,34 @@ impl BackupGroup {
     ) -> Result<Vec<BackupInfo>, Error> {
 
         let mut mark = HashMap::new();
-        
+
         BackupInfo::sort_list(&mut list, false);
-        
-        if let Some(keep_last) = keep_last {
-            for _ in 0..keep_last {
-                if list.is_empty() { break; }
-                let info = list.remove(0);
+
+        // remove inclomplete snapshots
+        let mut keep_unfinished = true;
+        for info in list.iter() {
+            // backup is considered unfinished if there is no manifest
+            if info.files.iter().any(|name| name == super::MANIFEST_BLOB_NAME) {
+                // There is a new finished backup, so there is no need
+                // to keep older unfinished backups.
+                keep_unfinished = false;
+            } else {
                 let backup_id = info.backup_dir.relative_path();
-                mark.insert(backup_id, PruneMark::Keep);
+                if keep_unfinished { // keep first unfinished
+                    mark.insert(backup_id, PruneMark::Keep);
+                } else {
+                    mark.insert(backup_id, PruneMark::Remove);
+                }
+                keep_unfinished = false;
             }
         }
 
+        if let Some(keep_last) = keep_last {
+             Self::mark_selections(&mut mark, &list, keep_last as usize, |_local_time, info| {
+                 BackupDir::backup_time_to_string(info.backup_dir.backup_time)
+             });
+        }
+
         if let Some(keep_daily) = keep_daily {
             Self::mark_selections(&mut mark, &list, keep_daily as usize, |local_time, _info| {
                 format!("{}/{}/{}", local_time.year(), local_time.month(), local_time.day())
diff --git a/tests/prune_data/simple1/host/elsa/2019-12-02T11:59:15Z/index.json b/tests/prune_data/simple1/host/elsa/2019-12-02T11:59:15Z/index.json.blob
similarity index 100%
rename from tests/prune_data/simple1/host/elsa/2019-12-02T11:59:15Z/index.json
rename to tests/prune_data/simple1/host/elsa/2019-12-02T11:59:15Z/index.json.blob
diff --git a/tests/prune_data/simple1/host/elsa/2019-12-03T11:59:15Z/index.json b/tests/prune_data/simple1/host/elsa/2019-12-03T11:59:15Z/index.json.blob
similarity index 100%
rename from tests/prune_data/simple1/host/elsa/2019-12-03T11:59:15Z/index.json
rename to tests/prune_data/simple1/host/elsa/2019-12-03T11:59:15Z/index.json.blob
diff --git a/tests/prune_data/simple1/host/elsa/2019-12-04T11:59:15Z/index.json b/tests/prune_data/simple1/host/elsa/2019-12-04T11:59:15Z/index.json.blob
similarity index 100%
rename from tests/prune_data/simple1/host/elsa/2019-12-04T11:59:15Z/index.json
rename to tests/prune_data/simple1/host/elsa/2019-12-04T11:59:15Z/index.json.blob
diff --git a/tests/prune_data/simple1/host/elsa/2019-12-04T12:59:15Z/index.json b/tests/prune_data/simple1/host/elsa/2019-12-04T12:59:15Z/index.json.blob
similarity index 100%
rename from tests/prune_data/simple1/host/elsa/2019-12-04T12:59:15Z/index.json
rename to tests/prune_data/simple1/host/elsa/2019-12-04T12:59:15Z/index.json.blob