--- Chrysalis/analysis/RunButterfly.cc	2011-11-28 09:14:40.000000000 -0500
+++ Chrysalis/analysis/RunButterfly.cc	2015-12-15 16:54:00.000000000 -0500
@@ -1,3 +1,4 @@
+#include <unistd.h>
 #include <string>
 #include "base/CommandLineParser.h"
 #include "base/FileParser.h"
