diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index c667a29..6149434 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4452,6 +4452,7 @@
                                  ssl->handshake->psk_len);
         mbedtls_free(ssl->handshake->psk);
         ssl->handshake->psk_len = 0;
+        ssl->handshake->psk = NULL;
     }
 }