diff --git a/monitor/main.c b/monitor/main.c
index e9384e1b..8f354d52 100644
--- a/monitor/main.c
+++ b/monitor/main.c
@@ -32,6 +32,7 @@
 #include <string.h>
 #include <getopt.h>
 #include <signal.h>
+#include <unistd.h>
 #include <arpa/inet.h>
 #include <sys/socket.h>
 #include <linux/genetlink.h>