diff --git a/app/observatory/burst/healthping_result.go b/app/observatory/burst/healthping_result.go
index 4759c5e32..6ba5720d9 100644
--- a/app/observatory/burst/healthping_result.go
+++ b/app/observatory/burst/healthping_result.go
@@ -109,7 +109,7 @@ func (h *HealthPingRTTS) getStatistics() *HealthPingStats {
 		stats.Min = 0
 		return stats
 	}
-	stats.Average = time.Duration(int(sum) / cnt)
+	stats.Average = sum / time.Duration(cnt)
 	var std float64
 	if cnt < 2 {
 		// no enough data for standard deviation, we assume it's half of the average rtt
diff --git a/proxy/shadowsocks_2022/packet.go b/proxy/shadowsocks_2022/packet.go
index f81754575..310d3d7bd 100644
--- a/proxy/shadowsocks_2022/packet.go
+++ b/proxy/shadowsocks_2022/packet.go
@@ -153,7 +153,7 @@ func parsePlainUDPPacket(sessionID, packetID uint64, bodyPlain []byte) (DecodedU
 		return DecodedUDPPacket{}, ErrBadHeaderType
 	}
 	epoch := binary.BigEndian.Uint64(bodyPlain[1:9])
-	diff := int(math.Abs(float64(time.Now().Unix() - int64(epoch))))
+	diff := math.Abs(float64(time.Now().Unix() - int64(epoch)))
 	if diff > 30 {
 		return DecodedUDPPacket{}, ErrBadTimestamp
 	}
diff --git a/proxy/shadowsocks_2022/replay.go b/proxy/shadowsocks_2022/replay.go
index 241eb053c..056acbb2f 100644
--- a/proxy/shadowsocks_2022/replay.go
+++ b/proxy/shadowsocks_2022/replay.go
@@ -49,12 +49,12 @@ func (f *SlidingWindow) Add(counter uint64) {
 
 	if counter > f.last {
 		lastBlockIndex := f.last >> swBlockBitLog
-		diff := int(blockIndex - lastBlockIndex)
+		diff := blockIndex - lastBlockIndex
 		if diff > swRingBlocks {
 			diff = swRingBlocks
 		}
 
-		for i := 0; i < diff; i++ {
+		for i := 0; i < int(diff); i++ {
 			lastBlockIndex = (lastBlockIndex + 1) & swBlockMask
 			f.ring[lastBlockIndex] = 0
 		}
diff --git a/proxy/shadowsocks_2022/stream.go b/proxy/shadowsocks_2022/stream.go
index acde16155..0c22383c5 100644
--- a/proxy/shadowsocks_2022/stream.go
+++ b/proxy/shadowsocks_2022/stream.go
@@ -253,7 +253,7 @@ func ReadClientRequestHeaderWithFixed(reader *StreamReader, fixedChunk []byte) (
 	}
 
 	epoch := binary.BigEndian.Uint64(plainFixed[1:9])
-	diff := int(math.Abs(float64(time.Now().Unix() - int64(epoch))))
+	diff := math.Abs(float64(time.Now().Unix() - int64(epoch)))
 	if diff > 30 {
 		return nil, ErrBadTimestamp
 	}
@@ -430,7 +430,7 @@ func ReadTCPResponse(r io.Reader, method *CipherMethod, psk []byte, clientSalt [
 	}
 
 	serverEpoch := binary.BigEndian.Uint64(decryptedFixed[1:9])
-	diff := int(math.Abs(float64(time.Now().Unix() - int64(serverEpoch))))
+	diff := math.Abs(float64(time.Now().Unix() - int64(serverEpoch)))
 	if diff > 30 {
 		return nil, ErrBadTimestamp
 	}
diff --git a/transport/internet/xdrive/drive.go b/transport/internet/xdrive/drive.go
index 43f34e2f4..d5da0cfb4 100644
--- a/transport/internet/xdrive/drive.go
+++ b/transport/internet/xdrive/drive.go
@@ -153,7 +153,7 @@ func jitter(backoff time.Duration) time.Duration {
 	if half <= 0 {
 		return backoff
 	}
-	return half + time.Duration(dice.Roll(int(half)))
+	return half + time.Duration(dice.RollInt63n(int64(half)))
 }
 
 func rateLimited(payload []byte) bool {