diff --git a/lib/AST/InheritViz.cpp b/lib/AST/InheritViz.cpp
index 4438f01f63593b2cce8b6e9fa24a87dc94b33c72..6243faf32975e00e6ebcf96a70ad747e5b77ff39 100644
--- a/lib/AST/InheritViz.cpp
+++ b/lib/AST/InheritViz.cpp
@@ -21,6 +21,7 @@
 #include "llvm/Support/PathV1.h"
 #include "llvm/Support/raw_ostream.h"
 #include <map>
+#include <set>
 
 using namespace llvm;