diff --git a/internal/multiplex/obfs.go b/internal/multiplex/obfs.go
index 099ab08..733bb97 100644
--- a/internal/multiplex/obfs.go
+++ b/internal/multiplex/obfs.go
@@ -35,10 +35,10 @@ func MakeObfs(salsaKey [32]byte, payloadCipher cipher.AEAD) Obfser {
 		if len(buf) < usefulLen {
 			return 0, errors.New("buffer is too small")
 		}
-		used := buf[:usefulLen]
-		recordLayer := used[0:5]
-		header := used[5 : 5+HEADER_LEN]
-		encryptedPayload := used[5+HEADER_LEN:]
+		useful := buf[:usefulLen] // tls header + payload + potential overhead
+		recordLayer := useful[0:5]
+		header := useful[5 : 5+HEADER_LEN]
+		encryptedPayload := useful[5+HEADER_LEN:]
 
 		// header: [StreamID 4 bytes][Seq 4 bytes][Closing 1 byte][extraLen 1 bytes][random 2 bytes]
 		putU32(header[0:4], f.StreamID)
diff --git a/internal/multiplex/session_test.go b/internal/multiplex/session_test.go
index 3a0216f..b7b947a 100644
--- a/internal/multiplex/session_test.go
+++ b/internal/multiplex/session_test.go
@@ -25,14 +25,10 @@ func BenchmarkRecvDataFromRemote(b *testing.B) {
 		sesh := MakeSession(0, UNLIMITED_VALVE, obfuscator, util.ReadTLS)
 		n, _ := sesh.Obfs(f, obfsBuf)
 
-		originalHeader := make([]byte, 12)
-		copy(originalHeader, obfsBuf[5:17])
-
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
 			sesh.recvDataFromRemote(obfsBuf[:n])
 			b.SetBytes(int64(n))
-			copy(obfsBuf[5:17], originalHeader)
 		}
 	})
 
@@ -41,15 +37,10 @@ func BenchmarkRecvDataFromRemote(b *testing.B) {
 		sesh := MakeSession(0, UNLIMITED_VALVE, obfuscator, util.ReadTLS)
 		n, _ := sesh.Obfs(f, obfsBuf)
 
-		// because deobfs decrypts the header in-place, which alters the input
-		originalHeader := make([]byte, 12)
-		copy(originalHeader, obfsBuf[5:17])
-
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
 			sesh.recvDataFromRemote(obfsBuf[:n])
 			b.SetBytes(int64(n))
-			copy(obfsBuf[5:17], originalHeader)
 		}
 	})
 
@@ -58,14 +49,10 @@ func BenchmarkRecvDataFromRemote(b *testing.B) {
 		sesh := MakeSession(0, UNLIMITED_VALVE, obfuscator, util.ReadTLS)
 		n, _ := sesh.Obfs(f, obfsBuf)
 
-		originalHeader := make([]byte, 12)
-		copy(originalHeader, obfsBuf[5:17])
-
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
 			sesh.recvDataFromRemote(obfsBuf[:n])
 			b.SetBytes(int64(n))
-			copy(obfsBuf[5:17], originalHeader)
 		}
 	})