diff --git a/include/mraa_internal_types.h b/include/mraa_internal_types.h
index 41ed831..07d7b2a 100644
--- a/include/mraa_internal_types.h
+++ b/include/mraa_internal_types.h
@@ -92,6 +92,7 @@ struct _uart {
     /*@{*/
     int index; /**< the uart index, as known to the os. */
     char* path; /**< the uart device path. */
+    int fd; /**< file descriptor for device. */
     /*@}*/
 };
 
diff --git a/src/uart/uart.c b/src/uart/uart.c
index d3dc0d8..aba7b66 100644
--- a/src/uart/uart.c
+++ b/src/uart/uart.c
@@ -83,6 +83,7 @@ mraa_uart_init(int index)
     memset(dev, 0, sizeof(struct _uart));
 
     dev->index = index;
+    dev->fd = -1;
     dev->path = (char*) plat->uart_dev[index].device_path;
     if (advance_func->uart_init_post != NULL) {
         mraa_result_t ret = advance_func->uart_init_post(dev);