diff --git a/lib/VMCore/Dominators.cpp b/lib/VMCore/Dominators.cpp
index 1d7553c2b3b..0ddc370f477 100644
--- a/lib/VMCore/Dominators.cpp
+++ b/lib/VMCore/Dominators.cpp
@@ -20,6 +20,7 @@
 #include "llvm/ADT/DepthFirstIterator.h"
 #include "llvm/ADT/SetOperations.h"
 #include <algorithm>
+#include <iostream>
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//