diff --git a/lib/Sema/SemaAttr.cpp b/lib/Sema/SemaAttr.cpp
index e2eb87f..5769716 100644
--- a/lib/Sema/SemaAttr.cpp
+++ b/lib/Sema/SemaAttr.cpp
@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "Sema.h"
+#include "Lookup.h"
 #include "clang/AST/Expr.h"
 using namespace clang;