diff --git a/src/main_utils.cpp b/src/main_utils.cpp
index 70cf39b740f0b90a0286bd92954db0a2c58c524c..05714cc5b1f90929da976bce950343f339c0280c 100644
--- a/src/main_utils.cpp
+++ b/src/main_utils.cpp
@@ -5,6 +5,7 @@
  *      Author: vlegrand
  */
 
+#include <unistd.h>
 #include <sys/types.h>
 #include <sys/sysctl.h>
 #include <sys/stat.h>