diff --git a/ports/zephyr/src/zephyr_start.c b/ports/zephyr/src/zephyr_start.c
index e15f874b1..c37af8e5b 100644
--- a/ports/zephyr/src/zephyr_start.c
+++ b/ports/zephyr/src/zephyr_start.c
@@ -29,11 +29,13 @@
 int real_main(void);
 int mp_console_init(void);
 
-void main(void) {
+int main(void) {
     #ifdef CONFIG_CONSOLE_SUBSYS
     mp_console_init();
     #else
     zephyr_getchar_init();
     #endif
     real_main();
+
+    return 0;
 }