diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 8bd74db8d..b671c14ac 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -8741,6 +8741,7 @@ static void ssl_buffering_free_slot( mbedtls_ssl_context *ssl,
     if( hs_buf->is_valid == 1 )
     {
         hs->buffering.total_bytes_buffered -= hs_buf->data_len;
+        mbedtls_platform_zeroize( hs_buf->data, hs_buf->data_len );
         mbedtls_free( hs_buf->data );
         memset( hs_buf, 0, sizeof( mbedtls_ssl_hs_buffer ) );
     }