diff -r be121cbf3284 -r 23e3cd901cb6 src/hotspot/share/jfr/recorder/checkpoint/jfrCheckpointWriter.cpp
--- a/src/hotspot/share/jfr/recorder/checkpoint/jfrCheckpointWriter.cpp	Mon Sep 02 21:08:41 2019 +0200
+++ b/src/hotspot/share/jfr/recorder/checkpoint/jfrCheckpointWriter.cpp	Tue Sep 03 11:48:31 2019 +0200
@@ -161,7 +161,7 @@
   *size = this->used_size();
   assert(this->start_pos() + *size == this->current_pos(), "invariant");
   write_checkpoint_header(const_cast<u1*>(this->start_pos()), this->used_offset(), _time, (u4)_type, count());
-  _header = false; // the header is already written
+  _header = false; // the header was just written
   if (move) {
     this->seek(_offset);
   }