diff --git a/cmd/thanos/sidecar.go b/cmd/thanos/sidecar.go
index 127584ea94..531ffb8ab4 100644
--- a/cmd/thanos/sidecar.go
+++ b/cmd/thanos/sidecar.go
@@ -505,7 +505,7 @@ func (s *promMetadata) UpdateTimestamps(ctx context.Context) error {
 		return err
 	}
 
-	s.mint = min(s.limitMinTime.PrometheusTimestamp(), mint)
+	s.mint = max(s.limitMinTime.PrometheusTimestamp(), mint)
 	s.maxt = math.MaxInt64
 
 	return nil