diff --git a/libraries/Update/src/Updater.cpp b/libraries/Update/src/Updater.cpp
index 4be13b9d1ed..c48d661c8d8 100644
--- a/libraries/Update/src/Updater.cpp
+++ b/libraries/Update/src/Updater.cpp
@@ -328,7 +328,7 @@ bool UpdateClass::_decryptBuffer() {
         return false;
       }
     }
-    if (mbedtls_aes_crypt_ecb(&ctx, MBEDTLS_AES_ENCRYPT, _cryptBuffer, _cryptBuffer)) {  //use MBEDTLS_AES_ENCRYPT to decrypt flash code
+    if (mbedtls_aes_crypt_ecb(&ctx, MBEDTLS_AES_DECRYPT, _cryptBuffer, _cryptBuffer)) {  //use MBEDTLS_AES_DECRYPT to decrypt flash code
       return false;
     }
     for (int i = 0; i < ENCRYPTED_BLOCK_SIZE; i++) {