diff --git a/io/vmess/vmess.go b/io/vmess/vmess.go
index 18a51a51..2f795299 100644
--- a/io/vmess/vmess.go
+++ b/io/vmess/vmess.go
@@ -2,7 +2,7 @@
 package vmess
 
 import (
-  "fmt"
+	"fmt"
 	"io"
 )
 
@@ -21,18 +21,17 @@ type VMessInput struct {
 }
 
 func Read(reader io.Reader) (input *VMessInput, err error) {
-  buffer := make([]byte, 17 /* version + user hash */)
-  nBytes, err := reader.Read(buffer)
-  if err != nil {
-    return
-  }
-  if nBytes != len(buffer) {
-    err = fmt.Errorf("Unexpected length of header %d", nBytes)
-    return
-  }
-  
-  return
+	buffer := make([]byte, 17 /* version + user hash */)
+	nBytes, err := reader.Read(buffer)
+	if err != nil {
+		return
+	}
+	if nBytes != len(buffer) {
+		err = fmt.Errorf("Unexpected length of header %d", nBytes)
+		return
+	}
+
+	return
 }
 
 type VMessOutput [4]byte
-
diff --git a/spec/vmess.md b/spec/vmess.md
index 91192dc1..9e51f8d0 100644
--- a/spec/vmess.md
+++ b/spec/vmess.md
@@ -10,7 +10,7 @@
 * 16 字节：md5(用户 VID + 'ASK')
 
 指令部分：
-* 1 字节：随机填充长度 M (M <= 32)
+* 1 字节：随机填充长度 M (0 < M <= 32)
 * M 字节：随机填充内容
 * 1 字节：保留，总是 0x00
 * 16 字节：请求数据 IV
@@ -29,7 +29,7 @@
   * 4 字节：IPv4
   * 1 字节长度 + 域名
   * 16 字节：IPv6
-* 1 字节：随机填充长度 M2 (M2 <= 32)
+* 1 字节：随机填充长度 M2 (0 < M2 <= 32)，使得指令部分长度为 16 的倍数字节
 * M2 字节：随机填充内容
 
 数据部分