diff --git a/src/threading/MsgThread.cc b/src/threading/MsgThread.cc
index c3f694cdc1..6a3d496325 100644
--- a/src/threading/MsgThread.cc
+++ b/src/threading/MsgThread.cc
@@ -4,6 +4,8 @@
 #include "MsgThread.h"
 #include "Manager.h"
 
+#include <unistd.h>
+
 using namespace threading;
 
 namespace threading  {