diff --git a/proxy/vmess/command/accounts.go b/proxy/vmess/command/accounts.go
index 5ba3996f4..b01c78770 100644
--- a/proxy/vmess/command/accounts.go
+++ b/proxy/vmess/command/accounts.go
@@ -80,7 +80,7 @@ func (this *SwitchAccount) Unmarshal(data []byte) error {
 	}
 	this.AlterIds = serial.ParseUint16(data[alterIdStart : alterIdStart+2])
 	levelStart := alterIdStart + 2
-	if len(data) < levelStart {
+	if len(data) < levelStart+1 {
 		return transport.CorruptedPacket
 	}
 	this.Level = vmess.UserLevel(data[levelStart])
diff --git a/proxy/vmess/command/accounts_fuzz.go b/proxy/vmess/command/testing/fuzzing/accounts_fuzz.go
similarity index 64%
rename from proxy/vmess/command/accounts_fuzz.go
rename to proxy/vmess/command/testing/fuzzing/accounts_fuzz.go
index 4e1c33117..325d2501e 100644
--- a/proxy/vmess/command/accounts_fuzz.go
+++ b/proxy/vmess/command/testing/fuzzing/accounts_fuzz.go
@@ -1,6 +1,10 @@
 // +build gofuzz
 
-package command
+package fuzzing
+
+import (
+	. "github.com/v2ray/v2ray-core/proxy/vmess/command"
+)
 
 func Fuzz(data []byte) int {
 	cmd := new(SwitchAccount)
diff --git a/proxy/vmess/command/testing/fuzzing/data/empty_host.corpus b/proxy/vmess/command/testing/fuzzing/data/empty_host.corpus
new file mode 100644
index 000000000..340adecd2
Binary files /dev/null and b/proxy/vmess/command/testing/fuzzing/data/empty_host.corpus differ