diff --git a/src/common.c b/src/common.c
index 8e82c5db..01129eca 100644
--- a/src/common.c
+++ b/src/common.c
@@ -36,6 +36,7 @@
 #include <net/if.h>
 #include <netinet/in.h>
 #include <pthread.h>
+#include <unistd.h>
 #include "diskio.h"
 
 /* check for OS and include appropriate headers */