diff --git a/rpc/rpcutil.go b/rpc/rpcutil.go
index ede10f061..3588ca5a5 100644
--- a/rpc/rpcutil.go
+++ b/rpc/rpcutil.go
@@ -182,7 +182,9 @@ func recordRPCCost(startTime time.Time, method string, err error) {
 	// Optimistically, val will not be nil except the first Call of method
 	// expvar uses sync.Map
 	// So, we try it first without lock
-	if val = expvar.Get(name); val == nil {
+	val = expvar.Get(name)
+	valC = expvar.Get(nameC)
+	if val == nil || valC == nil {
 		callRPCExpvarLock.Lock()
 		val = expvar.Get(name)
 		if val == nil {
@@ -191,9 +193,9 @@ func recordRPCCost(startTime time.Time, method string, err error) {
 		}
 		callRPCExpvarLock.Unlock()
 		val = expvar.Get(name)
+		valC = expvar.Get(nameC)
 	}
 	val.(mw.Metric).Add(costTime.Seconds())
-	valC = expvar.Get(nameC)
 	valC.(mw.Metric).Add(1)
 	return
 }
diff --git a/rpc/rpcutil_test.go b/rpc/rpcutil_test.go
index 90a432095..ebde85893 100644
--- a/rpc/rpcutil_test.go
+++ b/rpc/rpcutil_test.go
@@ -18,6 +18,7 @@ package rpc
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -443,3 +444,28 @@ func BenchmarkPersistentCaller_Call(b *testing.B) {
 
 	server.Stop()
 }
+
+func TestRecordRPCCost(t *testing.T) {
+	Convey("Bug: bad critical section for multiple values", t, func(c C) {
+		var (
+			start      = time.Now()
+			rounds     = 1000
+			concurrent = 10
+			wg         = &sync.WaitGroup{}
+			body       = func(i int) {
+				defer func() {
+					c.So(recover(), ShouldBeNil)
+					wg.Done()
+				}()
+				recordRPCCost(start, fmt.Sprintf("M%d", i), nil)
+			}
+		)
+		defer wg.Wait()
+		for i := 0; i < rounds; i++ {
+			for j := 0; j < concurrent; j++ {
+				wg.Add(1)
+				go body(i)
+			}
+		}
+	})
+}