Index: include/llvm/Support/raw_ostream.h
===================================================================
--- include/llvm/Support/raw_ostream.h
+++ include/llvm/Support/raw_ostream.h
@@ -530,7 +530,7 @@
   uint64_t current_pos() const override;
 
 public:
-  explicit raw_null_ostream() {}
+  explicit raw_null_ostream() : raw_pwrite_stream(true) {}
   ~raw_null_ostream() override;
 };