diff --git a/libs/ardour/audiofile_tagger.cc b/libs/ardour/audiofile_tagger.cc
index 45cf59c10d..591b8e9238 100644
--- a/libs/ardour/audiofile_tagger.cc
+++ b/libs/ardour/audiofile_tagger.cc
@@ -48,7 +48,7 @@ AudiofileTagger::tag_file (std::string const& filename, SessionMetadata const& m
 
 	TagLib::FileRef file (filename.c_str ());
 	if (file.isNull ()) {
-		std::cerr << "TagLib::FileRef is null for file" << filename << std::endl;
+		std::cerr << "TagLib::FileRef is null for file '" << filename << "'" << std::endl;
 		return true; // continue anyway?!
 	}
 
diff --git a/libs/ardour/export_handler.cc b/libs/ardour/export_handler.cc
index ebd19271b0..702b497194 100644
--- a/libs/ardour/export_handler.cc
+++ b/libs/ardour/export_handler.cc
@@ -369,6 +369,10 @@ ExportHandler::finish_timespan ()
 
 	while (config_map.begin() != timespan_bounds.second) {
 
+		// XXX single timespan+format may produce multiple files
+		// e.g export selection == session
+		// -> TagLib::FileRef is null
+
 		ExportFormatSpecPtr fmt = config_map.begin()->second.format;
 		std::string filename = config_map.begin()->second.filename->get_path(fmt);
 		if (fmt->with_cue()) {