diff --git a/libs/ardour/ardour/beats_frames_converter.h b/libs/ardour/ardour/beats_frames_converter.h
index e76588ccaa..ee79430e4e 100644
--- a/libs/ardour/ardour/beats_frames_converter.h
+++ b/libs/ardour/ardour/beats_frames_converter.h
@@ -29,9 +29,9 @@ namespace ARDOUR {
 
 class TempoMap;
 
-/** Converter between beats and frames.  Takes durations in beats or frames
- *  and converts them using the tempo at the \a origin supplied to the constructor.
- *  Note that this does not covert positions, only durations.
+/** Converter between beats and frames.  Takes distances in beats or frames
+ *  from some origin (supplied to the constructor in frames), and converts
+ *  them to the opposite unit, taking tempo changes into account.
  */
 class BeatsFramesConverter : public Evoral::TimeConverter<double,framepos_t> {
 public:
diff --git a/libs/ardour/beats_frames_converter.cc b/libs/ardour/beats_frames_converter.cc
index f5d1794abb..03a581e276 100644
--- a/libs/ardour/beats_frames_converter.cc
+++ b/libs/ardour/beats_frames_converter.cc
@@ -24,6 +24,10 @@
 
 namespace ARDOUR {
 
+/** Takes a duration in beats and considers it as a distance from the origin
+ *  supplied to the constructor.  Returns the equivalent number of frames,
+ *  taking tempo changes into account.
+ */
 framecnt_t
 BeatsFramesConverter::to (double beats) const
 {
@@ -32,6 +36,10 @@ BeatsFramesConverter::to (double beats) const
 	return _tempo_map.framepos_plus_beats (_origin_b, beats) - _origin_b;
 }
 
+/** Takes a duration in frames and considers it as a distance from the origin
+ *  supplied to the constructor.  Returns the equivalent number of beats,
+ *  taking tempo changes into account.
+ */
 double
 BeatsFramesConverter::from (framecnt_t frames) const
 {