diff --git a/clang/include/clang/Serialization/ASTReader.h b/clang/include/clang/Serialization/ASTReader.h
index a4c7f54ab9e8b..2002bf23c9595 100644
--- a/clang/include/clang/Serialization/ASTReader.h
+++ b/clang/include/clang/Serialization/ASTReader.h
@@ -721,6 +721,7 @@ class ASTReader
     unsigned ID;
 
     /// Whether this is a wildcard export.
+    LLVM_PREFERRED_TYPE(bool)
     unsigned IsWildcard : 1;
 
     /// String data.