diff --git a/libs/main/application/pisystemmonitor.cpp b/libs/main/application/pisystemmonitor.cpp
index 4454273e..522df17b 100644
--- a/libs/main/application/pisystemmonitor.cpp
+++ b/libs/main/application/pisystemmonitor.cpp
@@ -19,6 +19,8 @@
 
 #include "pisystemmonitor.h"
 
+#include <unistd.h>
+
 #include "pidir.h"
 #include "piliterals_string.h"
 #include "piprocess.h"