diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 1adf960..f5cd977 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_CRYPTO_IN_PROGRESS                -0x7000  /**< A cryptographic operation is in progress. Try again later. */
+#define MBEDTLS_ERR_SSL_BAD_CONFIG                        -0x5E80  /**< Invalid value in SSL config */
 
 /*
  * Various constants