diff --git a/pg253/metrics.py b/pg253/metrics.py
index c3b7e65..74b44a1 100644
--- a/pg253/metrics.py
+++ b/pg253/metrics.py
@@ -68,9 +68,9 @@ def _readRemoteBackup(self):
     def refreshMetrics(self):
         for database in Remote.BACKUPS:
             (self.first_backup.labels(database)
-             .set(min(Remote.BACKUPS[database])[0].timestamp()))
+             .set(min(Remote.BACKUPS[database], default=0)[0].timestamp()))
             (self.last_backup.labels(database)
-             .set(max(Remote.BACKUPS[database])[0].timestamp()))
+             .set(max(Remote.BACKUPS[database], default=0)[0].timestamp()))
 
     def removeBackup(self, database, date, size):
         self.backups.remove(database, date.strftime('%Y%m%d-%H%M'), size)