diff --git a/bacnet-stack/demo/handler/s_arfs.c b/bacnet-stack/demo/handler/s_arfs.c
index 8d3cb252..a46beba2 100644
--- a/bacnet-stack/demo/handler/s_arfs.c
+++ b/bacnet-stack/demo/handler/s_arfs.c
@@ -25,6 +25,7 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <errno.h>
+#include <string.h>
 #include "config.h"
 #include "config.h"
 #include "txbuf.h"
diff --git a/bacnet-stack/demo/handler/s_awfs.c b/bacnet-stack/demo/handler/s_awfs.c
index ade1a64f..522d13ba 100644
--- a/bacnet-stack/demo/handler/s_awfs.c
+++ b/bacnet-stack/demo/handler/s_awfs.c
@@ -25,6 +25,7 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <errno.h>
+#include <string.h>
 #include "config.h"
 #include "config.h"
 #include "txbuf.h"
diff --git a/bacnet-stack/demo/handler/s_rd.c b/bacnet-stack/demo/handler/s_rd.c
index af556853..31915466 100644
--- a/bacnet-stack/demo/handler/s_rd.c
+++ b/bacnet-stack/demo/handler/s_rd.c
@@ -25,6 +25,7 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <errno.h>
+#include <string.h>
 #include "config.h"
 #include "config.h"
 #include "txbuf.h"
diff --git a/bacnet-stack/demo/handler/s_ts.c b/bacnet-stack/demo/handler/s_ts.c
index 523c7fb6..96ca70e0 100644
--- a/bacnet-stack/demo/handler/s_ts.c
+++ b/bacnet-stack/demo/handler/s_ts.c
@@ -25,6 +25,7 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <errno.h>
+#include <string.h>
 #include "config.h"
 #include "config.h"
 #include "txbuf.h"
diff --git a/bacnet-stack/demo/handler/s_whohas.c b/bacnet-stack/demo/handler/s_whohas.c
index 37013d80..1ef7f68d 100644
--- a/bacnet-stack/demo/handler/s_whohas.c
+++ b/bacnet-stack/demo/handler/s_whohas.c
@@ -25,6 +25,7 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <errno.h>
+#include <string.h>
 #include "config.h"
 #include "config.h"
 #include "txbuf.h"