diff --git a/openbsd-compat/port-linux.c b/openbsd-compat/port-linux.c
index df7290246df6..4c024c6d2d61 100644
--- a/openbsd-compat/port-linux.c
+++ b/openbsd-compat/port-linux.c
@@ -33,6 +33,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>
+#include <unistd.h>
 
 #include "log.h"
 #include "xmalloc.h"