diff --git a/include/polarssl/config.h b/include/polarssl/config.h
index e83518a..d43365f 100644
--- a/include/polarssl/config.h
+++ b/include/polarssl/config.h
@@ -2154,6 +2154,7 @@
 /* SSL options */
 //#define SSL_MAX_CONTENT_LEN             16384 /**< Size of the input / output buffer */
 //#define SSL_DEFAULT_TICKET_LIFETIME     86400 /**< Lifetime of session tickets (if enabled) */
+//#define POLARSSL_PSK_MAX_LEN               32 /**< Max size of TLS pre-shared keys, in bytes (default 256 bits) */
 
 /**
  * Complete list of ciphersuites to use, in order of preference.