diff --git a/src/ledger/file.go b/src/ledger/file.go
index fe48b8d..f62fd8c 100644
--- a/src/ledger/file.go
+++ b/src/ledger/file.go
@@ -25,6 +25,10 @@ func NewFiles(p string, q ...string) (Files, error) {
 	return f, err
 }
 
+func (files Files) Amend(old, now Delta) error {
+	return io.EOF
+}
+
 func (files Files) TempGetLastNLines(n int) ([]string, error) {
 	p := files.paths()[0]
 	f, err := os.Open(p)