diff --git a/Cantera/src/transport/MMCollisionInt.cpp b/Cantera/src/transport/MMCollisionInt.cpp
index d90869c19..f1f76e0c6 100755
--- a/Cantera/src/transport/MMCollisionInt.cpp
+++ b/Cantera/src/transport/MMCollisionInt.cpp
@@ -18,6 +18,7 @@
 #include "MMCollisionInt.h"
 #include "../polyfit.h"
 #include "../xml.h"
+#include "../XML_Writer.h"
 #include <stdio.h>
 
 namespace Cantera {