diff --git a/include/nuttx/serial/uart_16550.h b/include/nuttx/serial/uart_16550.h
index 8c4318f4bd3..32e95759d82 100644
--- a/include/nuttx/serial/uart_16550.h
+++ b/include/nuttx/serial/uart_16550.h
@@ -27,6 +27,7 @@
  ****************************************************************************/
 
 #include <nuttx/config.h>
+#include <stdint.h>
 
 #ifdef CONFIG_16550_UART