diff --git a/src/packet/public_key_encrypted_session_key.js b/src/packet/public_key_encrypted_session_key.js
index 887c62f6..8f2cd3ae 100644
--- a/src/packet/public_key_encrypted_session_key.js
+++ b/src/packet/public_key_encrypted_session_key.js
@@ -278,6 +278,7 @@ function decodeSessionKey(version, keyAlgo, decryptedData, randomSessionKey) {
     case enums.publicKey.x25519:
     case enums.publicKey.x448:
       return {
+        sessionKeyAlgorithm: null,
         sessionKey: decryptedData
       };
     default: