diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index d435a69..df62069 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -123,6 +123,7 @@
 #define MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS                 -0x6500  /**< The asynchronous operation is not completed yet. */
 #define MBEDTLS_ERR_SSL_EARLY_MESSAGE                     -0x6480  /**< Internal-only message signaling that a message arrived early. */
 #define MBEDTLS_ERR_SSL_UNEXPECTED_CID                    -0x6000  /**< An encrypted DTLS-frame with an unexpected CID was received. */
+#define MBEDTLS_ERR_SSL_VERSION_MISMATCH                  -0x5F00  /**< An operation failed due to an unexpected version or configuration. */
 #define MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS                -0x7000  /**< A cryptographic operation is in progress. Try again later. */
 
 /*
@@ -2179,6 +2180,9 @@
  * \return         \c 0 if successful.
  * \return         #MBEDTLS_ERR_SSL_ALLOC_FAILED if memory allocation failed.
  * \return         #MBEDTLS_ERR_SSL_BAD_INPUT_DATA if input data is invalid.
+ * \return         #MBEDTLS_ERR_SSL_VERSION_MISMATCH if the serialized data
+ *                 was generated in a different version or configuration of
+ *                 Mbed TLS.
  * \return         Another negative value for other kinds of errors (for
  *                 example, unsupported features in the embedded certificate).
  */