diff --git a/ChangeLog b/ChangeLog
index 290f775..8a25860 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,9 @@
 = mbed TLS 2.2.0 released 2015-10-xx
 
 Security
+   * Fix potential double free if mbedtls_ssl_conf_psk() is called more than
+     once and some allocation fails. Cannot be forced remotely. Found by Guido
+     Vranken, Intelworks.
    * The X509 max_pathlen constraint was not enforced on intermediate
      certificates. Found by Nicholas Wilson, fix and tests provided by
      Janos Follath. #280 and #319
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 4577849..8969b4b 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -5772,6 +5772,8 @@
     {
         mbedtls_free( conf->psk );
         mbedtls_free( conf->psk_identity );
+        conf->psk = NULL;
+        conf->psk_identity = NULL;
     }
 
     if( ( conf->psk = mbedtls_calloc( 1, psk_len ) ) == NULL ||