diff --git a/base/disk_units.cc b/base/disk_units.cc
index 04de8ad..66f71a2 100644
--- a/base/disk_units.cc
+++ b/base/disk_units.cc
@@ -1,7 +1,8 @@
 #include "base/disk_units.h"
 
-#include <stdexcept>
 #include <boost/lexical_cast.hpp>
+#include <cmath>
+#include <stdexcept>
 
 using namespace std;
 using namespace boost;