diff --git a/c++/sys/source/OSUnix.cpp b/c++/sys/source/OSUnix.cpp
index 0f03e6c..9b30c40 100644
--- a/c++/sys/source/OSUnix.cpp
+++ b/c++/sys/source/OSUnix.cpp
@@ -25,6 +25,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <limits.h>
 
 #include "sys/OSUnix.h"
 #include "sys/File.h"