diff --git a/device/cookie.go b/device/cookie.go
index 3a88a0c..f134128 100644
--- a/device/cookie.go
+++ b/device/cookie.go
@@ -87,7 +87,7 @@ func (st *CookieChecker) CheckMAC2(msg []byte, src []byte) bool {
 	st.RLock()
 	defer st.RUnlock()
 
-	if time.Now().Sub(st.mac2.secretSet) > CookieRefreshTime {
+	if time.Since(st.mac2.secretSet) > CookieRefreshTime {
 		return false
 	}
 
@@ -124,7 +124,7 @@ func (st *CookieChecker) CreateReply(
 
 	// refresh cookie secret
 
-	if time.Now().Sub(st.mac2.secretSet) > CookieRefreshTime {
+	if time.Since(st.mac2.secretSet) > CookieRefreshTime {
 		st.RUnlock()
 		st.Lock()
 		_, err := rand.Read(st.mac2.secret[:])
@@ -239,7 +239,7 @@ func (st *CookieGenerator) AddMacs(msg []byte) {
 
 	// set mac2
 
-	if time.Now().Sub(st.mac2.cookieSet) > CookieRefreshTime {
+	if time.Since(st.mac2.cookieSet) > CookieRefreshTime {
 		return
 	}
 
diff --git a/device/noise-protocol.go b/device/noise-protocol.go
index 1f70e81..dd75cc3 100644
--- a/device/noise-protocol.go
+++ b/device/noise-protocol.go
@@ -301,7 +301,7 @@ func (device *Device) ConsumeMessageInitiation(msg *MessageInitiation) *Peer {
 
 	var ok bool
 	ok = timestamp.After(handshake.lastTimestamp)
-	ok = ok && time.Now().Sub(handshake.lastInitiationConsumption) > HandshakeInitationRate
+	ok = ok && time.Since(handshake.lastInitiationConsumption) > HandshakeInitationRate
 	handshake.mutex.RUnlock()
 	if !ok {
 		return nil
diff --git a/device/receive.go b/device/receive.go
index 22870f2..32d632b 100644
--- a/device/receive.go
+++ b/device/receive.go
@@ -79,7 +79,7 @@ func (peer *Peer) keepKeyFreshReceiving() {
 		return
 	}
 	keypair := peer.keypairs.Current()
-	if keypair != nil && keypair.isInitiator && time.Now().Sub(keypair.created) > (RejectAfterTime-KeepaliveTimeout-RekeyTimeout) {
+	if keypair != nil && keypair.isInitiator && time.Since(keypair.created) > (RejectAfterTime-KeepaliveTimeout-RekeyTimeout) {
 		peer.timers.sentLastMinuteHandshake.Set(true)
 		peer.SendHandshakeInitiation(false)
 	}
diff --git a/device/send.go b/device/send.go
index ae96aa2..2198427 100644
--- a/device/send.go
+++ b/device/send.go
@@ -129,14 +129,14 @@ func (peer *Peer) SendHandshakeInitiation(isRetry bool) error {
 	}
 
 	peer.handshake.mutex.RLock()
-	if time.Now().Sub(peer.handshake.lastSentHandshake) < RekeyTimeout {
+	if time.Since(peer.handshake.lastSentHandshake) < RekeyTimeout {
 		peer.handshake.mutex.RUnlock()
 		return nil
 	}
 	peer.handshake.mutex.RUnlock()
 
 	peer.handshake.mutex.Lock()
-	if time.Now().Sub(peer.handshake.lastSentHandshake) < RekeyTimeout {
+	if time.Since(peer.handshake.lastSentHandshake) < RekeyTimeout {
 		peer.handshake.mutex.Unlock()
 		return nil
 	}
@@ -232,7 +232,7 @@ func (peer *Peer) keepKeyFreshSending() {
 		return
 	}
 	nonce := atomic.LoadUint64(&keypair.sendNonce)
-	if nonce > RekeyAfterMessages || (keypair.isInitiator && time.Now().Sub(keypair.created) > RekeyAfterTime) {
+	if nonce > RekeyAfterMessages || (keypair.isInitiator && time.Since(keypair.created) > RekeyAfterTime) {
 		peer.SendHandshakeInitiation(false)
 	}
 }
@@ -390,7 +390,7 @@ func (peer *Peer) RoutineNonce() {
 
 				keypair = peer.keypairs.Current()
 				if keypair != nil && keypair.sendNonce < RejectAfterMessages {
-					if time.Now().Sub(keypair.created) < RejectAfterTime {
+					if time.Since(keypair.created) < RejectAfterTime {
 						break
 					}
 				}
diff --git a/ratelimiter/ratelimiter.go b/ratelimiter/ratelimiter.go
index 595e5a5..772c45a 100644
--- a/ratelimiter/ratelimiter.go
+++ b/ratelimiter/ratelimiter.go
@@ -76,7 +76,7 @@ func (rate *Ratelimiter) Init() {
 
 					for key, entry := range rate.tableIPv4 {
 						entry.Lock()
-						if time.Now().Sub(entry.lastTime) > garbageCollectTime {
+						if time.Since(entry.lastTime) > garbageCollectTime {
 							delete(rate.tableIPv4, key)
 						}
 						entry.Unlock()
@@ -84,7 +84,7 @@ func (rate *Ratelimiter) Init() {
 
 					for key, entry := range rate.tableIPv6 {
 						entry.Lock()
-						if time.Now().Sub(entry.lastTime) > garbageCollectTime {
+						if time.Since(entry.lastTime) > garbageCollectTime {
 							delete(rate.tableIPv6, key)
 						}
 						entry.Unlock()