diff --git a/testing/irtest/cmd.cxx b/testing/irtest/cmd.cxx
index 44d07f39f..70a939065 100644
--- a/testing/irtest/cmd.cxx
+++ b/testing/irtest/cmd.cxx
@@ -29,6 +29,7 @@
 #include <pthread.h>
 #include <stdio.h>
 #include <fcntl.h>
+#include <unistd.h>
 
 #include "enum.hpp"
 #include "cmd.hpp"