diff --git a/include/polarssl/ssl.h b/include/polarssl/ssl.h
index c682c0a..fbcbbea 100644
--- a/include/polarssl/ssl.h
+++ b/include/polarssl/ssl.h
@@ -132,6 +132,7 @@
 #define POLARSSL_ERR_SSL_SESSION_TICKET_EXPIRED            -0x6D80  /**< Session ticket has expired. */
 #define POLARSSL_ERR_SSL_PK_TYPE_MISMATCH                  -0x6D00  /**< Public key type mismatch (eg, asked for RSA key exchange and presented EC key) */
 #define POLARSSL_ERR_SSL_UNKNOWN_IDENTITY                  -0x6C80  /**< Unkown identity received (eg, PSK identity) */
+#define POLARSSL_ERR_SSL_INTERNAL_ERROR                    -0x6C00  /**< Internal error (eg, unexpected failure in lower-level module) */
 
 /*
  * Various constants