diff --git a/ports/zephyr/bip-init.c b/ports/zephyr/bip-init.c
index 58c020de..f36ea2b2 100644
--- a/ports/zephyr/bip-init.c
+++ b/ports/zephyr/bip-init.c
@@ -41,6 +41,9 @@
 #include <zephyr/net/net_ip.h>
 #include <zephyr/net/socket.h>
 #include <zephyr/net/socket_select.h>
+/* BACnet Stack defines - first */
+#include "bacnet/bacdef.h"
+/* BACnet Stack API */
 #include "bacnet/bacdcode.h"
 #include "bacnet/bacint.h"
 #include "bacnet/datalink/bip.h"
diff --git a/ports/zephyr/bip6-init.c b/ports/zephyr/bip6-init.c
index 69f6bae8..99e76760 100644
--- a/ports/zephyr/bip6-init.c
+++ b/ports/zephyr/bip6-init.c
@@ -41,6 +41,9 @@
 #include <net/net_ip.h>
 #include <net/socket.h>
 #include <net/socket_select.h>
+/* BACnet Stack defines - first */
+#include "bacnet/bacdef.h"
+/* BACnet Stack API */
 #include "bacnet/bacdcode.h"
 #include "bacnet/bacint.h"
 #include "bacnet/datalink/bip6.h"
diff --git a/ports/zephyr/datalink/bvlc.c b/ports/zephyr/datalink/bvlc.c
index 145e982b..f94316b9 100644
--- a/ports/zephyr/datalink/bvlc.c
+++ b/ports/zephyr/datalink/bvlc.c
@@ -31,7 +31,9 @@
  License.
  -------------------------------------------
 ####COPYRIGHTEND####*/
-
+/* BACnet Stack defines - first */
+#include "bacnet/bacdef.h"
+/* BACnet Stack API */
 #include "bacnet/datalink/bvlc.h"
 
 /**
diff --git a/ports/zephyr/datetime-init.c b/ports/zephyr/datetime-init.c
index 1882e1d7..cf6f18a6 100644
--- a/ports/zephyr/datetime-init.c
+++ b/ports/zephyr/datetime-init.c
@@ -14,6 +14,9 @@
 #include <stdlib.h>
 #include <time.h>
 #include <sys/time.h>
+/* BACnet Stack defines - first */
+#include "bacnet/bacdef.h"
+/* BACnet Stack API */
 #include "bacnet/datetime.h"
 
 
diff --git a/ports/zephyr/mstimer-init.c b/ports/zephyr/mstimer-init.c
index b8d44c2f..9f073577 100644
--- a/ports/zephyr/mstimer-init.c
+++ b/ports/zephyr/mstimer-init.c
@@ -24,6 +24,9 @@
 *
 *********************************************************************/
 #include <zephyr/kernel.h>
+/* BACnet Stack defines - first */
+#include "bacnet/bacdef.h"
+/* BACnet Stack API */
 #include "bacnet/basic/sys/mstimer.h"
 
 /**