diff --git a/src/cmds/restic/cmd_prune.go b/src/cmds/restic/cmd_prune.go
index a7f81da38..d9306c34c 100644
--- a/src/cmds/restic/cmd_prune.go
+++ b/src/cmds/restic/cmd_prune.go
@@ -180,22 +180,22 @@ func (cmd CmdPrune) Execute(args []string) error {
 		return err
 	}
 
-	id, err := idx.Save(repo)
+	var supersedes backend.IDs
+	for idxID := range repo.List(backend.Index, done) {
+		err := repo.Backend().Remove(backend.Index, idxID.String())
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "unable to remove index %v: %v\n", idxID.Str(), err)
+		}
+
+		supersedes = append(supersedes, idxID)
+	}
+
+	id, err := idx.Save(repo, supersedes)
 	if err != nil {
 		return err
 	}
 	cmd.global.Verbosef("saved new index as %v\n", id.Str())
 
-	for oldIndex := range repo.List(backend.Index, done) {
-		if id.Equal(oldIndex) {
-			continue
-		}
-		err := repo.Backend().Remove(backend.Index, oldIndex.String())
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "unable to remove index %v: %v\n", oldIndex.Str(), err)
-		}
-	}
-
 	cmd.global.Verbosef("done\n")
 	return nil
 }
diff --git a/src/restic/index/index.go b/src/restic/index/index.go
index 6bd934dc1..887e1234a 100644
--- a/src/restic/index/index.go
+++ b/src/restic/index/index.go
@@ -287,15 +287,14 @@ func (idx *Index) FindBlob(h pack.Handle) ([]Location, error) {
 	return result, nil
 }
 
-// Save writes the complete index to the repo and includes all previously read
-// indexes to the Supersedes field.
-func (idx *Index) Save(repo types.Repository) (backend.ID, error) {
+// Save writes the complete index to the repo.
+func (idx *Index) Save(repo types.Repository, supersedes backend.IDs) (backend.ID, error) {
 	packs := make(map[backend.ID][]pack.Blob, len(idx.Packs))
 	for id, p := range idx.Packs {
 		packs[id] = p.Entries
 	}
 
-	return Save(repo, packs, idx.IndexIDs.List())
+	return Save(repo, packs, supersedes)
 }
 
 // Save writes a new index containing the given packs.