diff --git a/internal/restic/idset.go b/internal/restic/idset.go
index 1b12a6398..9e6e3c6fd 100644
--- a/internal/restic/idset.go
+++ b/internal/restic/idset.go
@@ -105,3 +105,9 @@ func (s IDSet) String() string {
 	str := s.List().String()
 	return "{" + str[1:len(str)-1] + "}"
 }
+
+func (s IDSet) Clone() IDSet {
+	c := NewIDSet()
+	c.Merge(s)
+	return c
+}
diff --git a/internal/restic/idset_test.go b/internal/restic/idset_test.go
index 734b31237..14c88b314 100644
--- a/internal/restic/idset_test.go
+++ b/internal/restic/idset_test.go
@@ -35,4 +35,7 @@ func TestIDSet(t *testing.T) {
 	}
 
 	rtest.Equals(t, "{1285b303 7bb086db f658198b}", set.String())
+
+	copied := set.Clone()
+	rtest.Equals(t, "{1285b303 7bb086db f658198b}", copied.String())
 }