diff --git a/lib/VMCore/Constants.cpp b/lib/VMCore/Constants.cpp
index 1ed6ed58b31..6aa218c74e7 100644
--- a/lib/VMCore/Constants.cpp
+++ b/lib/VMCore/Constants.cpp
@@ -21,6 +21,7 @@
 #include "llvm/ADT/StringExtras.h"
 #include <algorithm>
 #include <iostream>
+#include "math.h"
 using namespace llvm;
 
 ConstantBool *ConstantBool::True  = new ConstantBool(true);