diff --git a/lib/Support/FileUtilities.cpp b/lib/Support/FileUtilities.cpp
index 9f9ef306868..3e4c270da56 100644
--- a/lib/Support/FileUtilities.cpp
+++ b/lib/Support/FileUtilities.cpp
@@ -6,6 +6,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "Support/FileUtilities.h"
+#include "Config/unistd.h"
 #include <fstream>
 #include <iostream>
 #include <cstdio>
diff --git a/support/lib/Support/FileUtilities.cpp b/support/lib/Support/FileUtilities.cpp
index 9f9ef306868..3e4c270da56 100644
--- a/support/lib/Support/FileUtilities.cpp
+++ b/support/lib/Support/FileUtilities.cpp
@@ -6,6 +6,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "Support/FileUtilities.h"
+#include "Config/unistd.h"
 #include <fstream>
 #include <iostream>
 #include <cstdio>