diff --git a/bacnet-stack/demo/handler/h_rpm.c b/bacnet-stack/demo/handler/h_rpm.c
index 5ccd55c0..8899a427 100644
--- a/bacnet-stack/demo/handler/h_rpm.c
+++ b/bacnet-stack/demo/handler/h_rpm.c
@@ -28,6 +28,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <errno.h>
 #include "config.h"
 #include "txbuf.h"
 #include "memcopy.h"