diff --git a/backend/sftp/sftp.go b/backend/sftp/sftp.go
index 4361eed69..71c874f0b 100644
--- a/backend/sftp/sftp.go
+++ b/backend/sftp/sftp.go
@@ -10,6 +10,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"sort"
+	"syscall"
 
 	"github.com/juju/errors"
 	"github.com/pkg/sftp"
@@ -35,6 +36,9 @@ func startClient(program string, args ...string) (*SFTP, error) {
 	// send errors from ssh to stderr
 	cmd.Stderr = os.Stderr
 
+	// ignore signals sent to the parent (e.g. SIGINT)
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setsid: true}
+
 	// get stdin and stdout
 	wr, err := cmd.StdinPipe()
 	if err != nil {
@@ -452,6 +456,10 @@ func (s *SFTP) Close() error {
 	}
 
 	s.c.Close()
-	// TODO: add timeout after which the process is killed
+
+	if err := s.cmd.Process.Kill(); err != nil {
+		return err
+	}
+
 	return s.cmd.Wait()
 }
diff --git a/cmd/restic/lock.go b/cmd/restic/lock.go
index 5f6c18802..389241644 100644
--- a/cmd/restic/lock.go
+++ b/cmd/restic/lock.go
@@ -49,7 +49,9 @@ func lockRepository(repo *repository.Repository, exclusive bool) (*restic.Lock,
 }
 
 func unlockRepo(lock *restic.Lock) error {
+	debug.Log("unlockRepo", "unlocking repository")
 	if err := lock.Unlock(); err != nil {
+		debug.Log("unlockRepo", "error while unlocking: %v", err)
 		return err
 	}
 
@@ -67,8 +69,10 @@ func unlockAll() error {
 	debug.Log("unlockAll", "unlocking %d locks", len(globalLocks))
 	for _, lock := range globalLocks {
 		if err := lock.Unlock(); err != nil {
+			debug.Log("unlockAll", "error while unlocking: %v", err)
 			return err
 		}
+		debug.Log("unlockAll", "successfully removed lock")
 	}
 
 	return nil