diff --git a/src/port.c b/src/port.c
index a7df04e8..c62d9252 100644
--- a/src/port.c
+++ b/src/port.c
@@ -1,5 +1,7 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
+#include <assert.h>
 
 #include "picrin.h"
 #include "picrin/proc.h"