--- code/D3MFOpcPackage.cpp.orig	2017-12-11 13:22:45 UTC
+++ code/D3MFOpcPackage.cpp
@@ -55,6 +55,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 #include <map>
 #include <algorithm>
 #include <cassert>
+#include <stdlib.h>
 #include <contrib/unzip/unzip.h>
 #include "3MFXmlTags.h"
 
