diff --git a/aos/events/logging/logger.cc b/aos/events/logging/logger.cc
index b3472d7..e767427 100644
--- a/aos/events/logging/logger.cc
+++ b/aos/events/logging/logger.cc
@@ -328,10 +328,21 @@
 }
 
 LogReader::~LogReader() {
-  Deregister();
+  if (event_loop_factory_unique_ptr_) {
+    Deregister();
+  } else if (event_loop_factory_ != nullptr) {
+    LOG(FATAL) << "Must call Deregister before the SimulatedEventLoopFactory "
+                  "is destroyed";
+  }
   if (offset_fp_ != nullptr) {
     fclose(offset_fp_);
   }
+  // Zero out some buffers. It's easy to do use-after-frees on these, so make it
+  // more obvious.
+  if (remapped_configuration_buffer_) {
+    remapped_configuration_buffer_->Wipe();
+  }
+  log_file_header_.Wipe();
 }
 
 const Configuration *LogReader::logged_configuration() const {
diff --git a/aos/flatbuffers.h b/aos/flatbuffers.h
index 0a06e00..4aa0ff8 100644
--- a/aos/flatbuffers.h
+++ b/aos/flatbuffers.h
@@ -115,6 +115,10 @@
   absl::Span<const uint8_t> span() const {
     return absl::Span<const uint8_t>(data(), size());
   }
+
+  // Wipes out the data buffer. This is handy to mark an instance as freed, and
+  // make attempts to use it fail more obviously.
+  void Wipe() { memset(data(), 0, size()); }
 };
 
 // String backed flatbuffer.