diff --git a/estimator/estimator.go b/estimator/estimator.go
index ef7a14d..792f064 100644
--- a/estimator/estimator.go
+++ b/estimator/estimator.go
@@ -1,49 +1,47 @@
 package estimator
 
 import (
-	"sync"
 	"sync/atomic"
 	"time"
+
+	"sfu/rtptime"
 )
 
 type Estimator struct {
-	interval time.Duration
-	bytes    uint32
-	packets  uint32
-
-	mu           sync.Mutex
+	interval     uint64
+	time         uint64
+	bytes        uint32
+	packets      uint32
 	totalBytes   uint32
 	totalPackets uint32
 	rate         uint32
 	packetRate   uint32
-	time         time.Time
 }
 
 func New(interval time.Duration) *Estimator {
 	return &Estimator{
-		interval: interval,
-		time:     time.Now(),
+		interval: rtptime.FromDuration(interval, rtptime.JiffiesPerSec),
+		time:     rtptime.Now(rtptime.JiffiesPerSec),
 	}
 }
 
-func (e *Estimator) swap(now time.Time) {
-	interval := now.Sub(e.time)
+func (e *Estimator) swap(now uint64) {
+	tm := atomic.LoadUint64(&e.time)
+	jiffies := now - tm
 	bytes := atomic.SwapUint32(&e.bytes, 0)
 	packets := atomic.SwapUint32(&e.packets, 0)
 	atomic.AddUint32(&e.totalBytes, bytes)
 	atomic.AddUint32(&e.totalPackets, packets)
 
-	if interval < time.Millisecond {
-		e.rate = 0
-		e.packetRate = 0
-	} else {
-		e.rate = uint32(uint64(bytes*1000) /
-			uint64(interval/time.Millisecond))
-		e.packetRate = uint32(uint64(packets*1000) /
-			uint64(interval/time.Millisecond))
-
+	var rate, packetRate uint32
+	if jiffies >= rtptime.JiffiesPerSec/1000 {
+		rate = uint32(uint64(bytes) * rtptime.JiffiesPerSec / jiffies)
+		packetRate =
+			uint32(uint64(packets) * rtptime.JiffiesPerSec / jiffies)
 	}
-	e.time = now
+	atomic.StoreUint32(&e.rate, rate)
+	atomic.StoreUint32(&e.packetRate, packetRate)
+	atomic.StoreUint64(&e.time, now)
 }
 
 func (e *Estimator) Accumulate(count uint32) {
@@ -51,20 +49,17 @@ func (e *Estimator) Accumulate(count uint32) {
 	atomic.AddUint32(&e.packets, 1)
 }
 
-func (e *Estimator) estimate(now time.Time) (uint32, uint32) {
-	if now.Sub(e.time) > e.interval {
+func (e *Estimator) estimate(now uint64) (uint32, uint32) {
+	tm := atomic.LoadUint64(&e.time)
+	if now < tm || now-tm > e.interval {
 		e.swap(now)
 	}
 
-	return e.rate, e.packetRate
+	return atomic.LoadUint32(&e.rate), atomic.LoadUint32(&e.packetRate)
 }
 
 func (e *Estimator) Estimate() (uint32, uint32) {
-	now := time.Now()
-
-	e.mu.Lock()
-	defer e.mu.Unlock()
-	return e.estimate(now)
+	return e.estimate(rtptime.Now(rtptime.JiffiesPerSec))
 }
 
 func (e *Estimator) Totals() (uint32, uint32) {
diff --git a/estimator/estimator_test.go b/estimator/estimator_test.go
index 21ae682..7876347 100644
--- a/estimator/estimator_test.go
+++ b/estimator/estimator_test.go
@@ -2,18 +2,20 @@ package estimator
 
 import (
 	"testing"
-	"time"
+
+	"sfu/rtptime"
 )
 
 func TestEstimator(t *testing.T) {
-	now := time.Now()
-	e := New(time.Second)
+	now := rtptime.Jiffies()
+	e := New(rtptime.JiffiesPerSec)
 
 	e.estimate(now)
 	e.Accumulate(42)
 	e.Accumulate(128)
-	e.estimate(now.Add(time.Second))
-	rate, packetRate := e.estimate(now.Add(time.Second + time.Millisecond))
+	e.estimate(now + rtptime.JiffiesPerSec)
+	rate, packetRate :=
+		e.estimate(now + (rtptime.JiffiesPerSec * 1001) / 1000)
 
 	if rate != 42+128 {
 		t.Errorf("Expected %v, got %v", 42+128, rate)