diff --git a/cmd/adapter/adapter.go b/cmd/adapter/adapter.go
index 8d62c0f96..5caa3d65c 100644
--- a/cmd/adapter/adapter.go
+++ b/cmd/adapter/adapter.go
@@ -242,7 +242,6 @@ func main() {
 	cmd := &PrometheusAdapter{
 		PrometheusURL:         "https://localhost",
 		MetricsRelistInterval: 10 * time.Minute,
-		MetricsMaxAge:         20 * time.Minute,
 	}
 	cmd.Name = "prometheus-metrics-adapter"
 	cmd.addFlags()
@@ -251,6 +250,11 @@ func main() {
 		klog.Fatalf("unable to parse flags: %v", err)
 	}
 
+	// if --metrics-max-age is not set, make it equal to --metrics-relist-interval
+	if cmd.MetricsMaxAge == 0*time.Second {
+		cmd.MetricsMaxAge = cmd.MetricsRelistInterval
+	}
+
 	// make the prometheus client
 	promClient, err := cmd.makePromClient()
 	if err != nil {