diff --git a/src/datasources/grafana.rs b/src/datasources/grafana.rs
index c61171b..f4480a2 100644
--- a/src/datasources/grafana.rs
+++ b/src/datasources/grafana.rs
@@ -118,7 +118,7 @@ impl Metric for Grafana {
         Ok(r)
     }
 
-    fn boxed_clone(&self) -> Box<dyn Metric> {
+    fn boxed_clone(&self) -> Box<dyn Metric + Sync> {
         return Box::new(self.clone());
     }
 }
diff --git a/src/datasources/grafana/prometheus.rs b/src/datasources/grafana/prometheus.rs
index 8417e70..5707537 100644
--- a/src/datasources/grafana/prometheus.rs
+++ b/src/datasources/grafana/prometheus.rs
@@ -63,7 +63,7 @@ impl Metric for Prometheus {
         return prometheus::parse_result(value);
     }
 
-    fn boxed_clone(&self) -> Box<dyn Metric> {
+    fn boxed_clone(&self) -> Box<dyn Metric + Sync> {
         return Box::new(self.clone());
     }
 }
diff --git a/src/datasources/influx.rs b/src/datasources/influx.rs
index 86dc830..5aad531 100644
--- a/src/datasources/influx.rs
+++ b/src/datasources/influx.rs
@@ -90,7 +90,7 @@ impl Metric for Influx {
         return parse_result(value);
     }
 
-    fn boxed_clone(&self) -> Box<dyn Metric> {
+    fn boxed_clone(&self) -> Box<dyn Metric + Sync> {
         return Box::new(self.clone());
     }
 }
diff --git a/src/datasources/prometheus.rs b/src/datasources/prometheus.rs
index e4bebdc..30a5fa7 100644
--- a/src/datasources/prometheus.rs
+++ b/src/datasources/prometheus.rs
@@ -98,7 +98,7 @@ impl Metric for Prometheus {
         return parse_result(value);
     }
 
-    fn boxed_clone(&self) -> Box<dyn Metric> {
+    fn boxed_clone(&self) -> Box<dyn Metric + Sync> {
         return Box::new(self.clone());
     }
 }
diff --git a/src/metric.rs b/src/metric.rs
index edc4765..a1a1d59 100644
--- a/src/metric.rs
+++ b/src/metric.rs
@@ -59,7 +59,7 @@ impl Default for MetricResult {
 #[async_trait]
 pub trait Metric {
 
-    fn boxed_clone(&self) -> Box<dyn Metric>;
+    fn boxed_clone(&self) -> Box<dyn Metric + Sync>;
 
     // (to - from) / step < 10000
     async fn query_chunk(&self, from: u64, to: u64, step: u64) -> types::Result<MetricResult>;