diff --git a/core/src/layers/metrics.rs b/core/src/layers/metrics.rs
index b1e2c39303d..c7fc75fa1f1 100644
--- a/core/src/layers/metrics.rs
+++ b/core/src/layers/metrics.rs
@@ -69,19 +69,11 @@ use crate::*;
 /// let (recorder, exporter) = builder.build().expect("failed to build recorder/exporter");
 /// let recorder = builder.build_recorder().expect("failed to build recorder");
 /// ```
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Default)]
 pub struct MetricsLayer {
     path_label_level: usize,
 }
 
-impl Default for MetricsLayer {
-    fn default() -> Self {
-        Self {
-            path_label_level: 0,
-        }
-    }
-}
-
 impl MetricsLayer {
     /// Set the level of path label.
     ///