diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index 937035a..aafd0bc 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -24,6 +24,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/raw_ostream.h"
 
 namespace clang {
 struct ASTTemplateArgumentListInfo;