diff --git a/tikv-client-common/src/stats.rs b/tikv-client-common/src/stats.rs
index 8ecdcd1..2bd647a 100644
--- a/tikv-client-common/src/stats.rs
+++ b/tikv-client-common/src/stats.rs
@@ -1,8 +1,8 @@
 // Copyright 2018 TiKV Project Authors. Licensed under Apache-2.0.
 
-use crate::{util::duration_to_sec, Result};
+use crate::Result;
 use prometheus::{Histogram, HistogramVec, IntCounterVec};
-use std::time::Instant;
+use std::time::{Duration, Instant};
 
 pub struct RequestStats {
     start: Instant,
@@ -125,3 +125,11 @@ lazy_static! {
     )
     .unwrap();
 }
+
+/// Convert Duration to seconds.
+#[inline]
+fn duration_to_sec(d: Duration) -> f64 {
+    let nanos = f64::from(d.subsec_nanos());
+    // In most cases, we can't have so large Duration, so here just panic if overflow now.
+    d.as_secs() as f64 + (nanos / 1_000_000_000.0)
+}
diff --git a/tikv-client-common/src/util.rs b/tikv-client-common/src/util.rs
index 869a864..989074a 100644
--- a/tikv-client-common/src/util.rs
+++ b/tikv-client-common/src/util.rs
@@ -1,7 +1,5 @@
 // Copyright 2018 TiKV Project Authors. Licensed under Apache-2.0.
 
-use std::time::Duration;
-
 #[macro_export]
 macro_rules! internal_err {
     ($e:expr) => ({
@@ -14,11 +12,3 @@ macro_rules! internal_err {
         internal_err!(format!($f, $($arg),+))
     });
 }
-
-/// Convert Duration to seconds.
-#[inline]
-pub fn duration_to_sec(d: Duration) -> f64 {
-    let nanos = f64::from(d.subsec_nanos());
-    // In most cases, we can't have so large Duration, so here just panic if overflow now.
-    d.as_secs() as f64 + (nanos / 1_000_000_000.0)
-}