diff --git a/llvm/lib/Analysis/DataStructure/GraphChecker.cpp b/llvm/lib/Analysis/DataStructure/GraphChecker.cpp
index af8731e..a5a639c 100644
--- a/llvm/lib/Analysis/DataStructure/GraphChecker.cpp
+++ b/llvm/lib/Analysis/DataStructure/GraphChecker.cpp
@@ -27,6 +27,7 @@
 #include "llvm/Analysis/DSGraph.h"
 #include "Support/CommandLine.h"
 #include "llvm/Value.h"
+#include <iostream>
 #include <set>
 
 using namespace llvm;