diff --git a/include/polarssl/ssl.h b/include/polarssl/ssl.h
index 7a468c4..d5a2fc0 100644
--- a/include/polarssl/ssl.h
+++ b/include/polarssl/ssl.h
@@ -110,7 +110,7 @@
 #define POLARSSL_ERR_SSL_BAD_HS_PROTOCOL_VERSION           -0x6E80  /**< Handshake protocol not within min/max boundaries */
 #define POLARSSL_ERR_SSL_BAD_HS_NEW_SESSION_TICKET         -0x6E00  /**< Processing of the NewSessionTicket handshake message failed. */
 #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) */
 
 /*
  * Various constants