diff --git a/app/dns/nameserver.go b/app/dns/nameserver.go
index 678a1f7fd..6fef31d0a 100644
--- a/app/dns/nameserver.go
+++ b/app/dns/nameserver.go
@@ -1,13 +1,13 @@
 package dns
 
 import (
-	"math/rand"
 	"net"
 	"sync"
 	"time"
 
 	"github.com/v2ray/v2ray-core/app/dispatcher"
 	"github.com/v2ray/v2ray-core/common/alloc"
+	"github.com/v2ray/v2ray-core/common/dice"
 	"github.com/v2ray/v2ray-core/common/log"
 	v2net "github.com/v2ray/v2ray-core/common/net"
 	"github.com/v2ray/v2ray-core/transport/internet/udp"
@@ -84,7 +84,7 @@ func (this *UDPNameServer) AssignUnusedID(response chan<- *ARecord) uint16 {
 	}
 
 	for {
-		id = uint16(rand.Intn(65536))
+		id = uint16(dice.Roll(65536))
 		if _, found := this.requests[id]; found {
 			continue
 		}
diff --git a/common/protocol/time.go b/common/protocol/time.go
index d1bae5cfe..454d1c15e 100644
--- a/common/protocol/time.go
+++ b/common/protocol/time.go
@@ -1,9 +1,9 @@
 package protocol
 
 import (
-	"math/rand"
 	"time"
 
+	"github.com/v2ray/v2ray-core/common/dice"
 	"github.com/v2ray/v2ray-core/common/serial"
 )
 
@@ -21,7 +21,7 @@ func NowTime() Timestamp {
 
 func NewTimestampGenerator(base Timestamp, delta int) TimestampGenerator {
 	return func() Timestamp {
-		rangeInDelta := rand.Intn(delta*2) - delta
+		rangeInDelta := dice.Roll(delta*2) - delta
 		return base + Timestamp(rangeInDelta)
 	}
 }
diff --git a/transport/internet/kcp/dialer.go b/transport/internet/kcp/dialer.go
index a33294696..0e0b3f143 100644
--- a/transport/internet/kcp/dialer.go
+++ b/transport/internet/kcp/dialer.go
@@ -1,9 +1,9 @@
 package kcp
 
 import (
-	"math/rand"
 	"net"
 
+	"github.com/v2ray/v2ray-core/common/dice"
 	"github.com/v2ray/v2ray-core/common/log"
 	v2net "github.com/v2ray/v2ray-core/common/net"
 	"github.com/v2ray/v2ray-core/transport/internet"
@@ -18,7 +18,7 @@ func DialKCP(src v2net.Address, dest v2net.Destination) (internet.Connection, er
 	}
 
 	cpip := NewSimpleAuthenticator()
-	session := NewConnection(uint16(rand.Uint32()), conn, conn.LocalAddr().(*net.UDPAddr), conn.RemoteAddr().(*net.UDPAddr), cpip)
+	session := NewConnection(uint16(dice.Roll(65536)), conn, conn.LocalAddr().(*net.UDPAddr), conn.RemoteAddr().(*net.UDPAddr), cpip)
 	session.FetchInputFrom(conn)
 
 	return session, nil