diff --git a/pkg/repository/postgres.go b/pkg/repository/postgres.go
index b6f59c6..607f737 100644
--- a/pkg/repository/postgres.go
+++ b/pkg/repository/postgres.go
@@ -891,6 +891,10 @@ func (d *Postgres) Import(ctx context.Context, src Repository) error {
 	}
 
 	sensors, err := src.GetSensors(ctx)
+	if err != nil {
+		return err
+	}
+
 	err = d.insertOrUpdateSensors(tx, sensors...)
 	if err != nil {
 		return err
diff --git a/pkg/repository/sqlite.go b/pkg/repository/sqlite.go
index 7d87327..75f6dc0 100644
--- a/pkg/repository/sqlite.go
+++ b/pkg/repository/sqlite.go
@@ -921,6 +921,9 @@ func (d *SQLite) GetTemperatures(ctx context.Context) ([]*types.MeasuredValue, e
 // Import imports devices, sensors and all measured values from a source
 // repository. Existing entries will be updated.
 func (d *SQLite) Import(ctx context.Context, src Repository) error {
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+
 	tx, err := d.dbo.BeginTx(ctx, &sql.TxOptions{ReadOnly: false})
 	if err != nil {
 		return err
@@ -938,6 +941,10 @@ func (d *SQLite) Import(ctx context.Context, src Repository) error {
 	}
 
 	sensors, err := src.GetSensors(ctx)
+	if err != nil {
+		return err
+	}
+
 	err = d.insertOrUpdateSensors(tx, sensors...)
 	if err != nil {
 		return err