diff --git a/libs/ardour/ardour/audioregion.h b/libs/ardour/ardour/audioregion.h
index 07a6e99dec..317363182d 100644
--- a/libs/ardour/ardour/audioregion.h
+++ b/libs/ardour/ardour/audioregion.h
@@ -289,6 +289,7 @@ class LIBARDOUR_API AudioRegion : public Region, public AudioReadable
 
 	int _set_state (const XMLNode&, int version, PBD::PropertyChange& what_changed, bool send_signal);
 	void send_change (const PBD::PropertyChange&);
+	void ensure_length_sanity ();
 };
 
 } /* namespace ARDOUR */
diff --git a/libs/ardour/ardour/region.h b/libs/ardour/ardour/region.h
index df7b83484a..5d3c9fe39f 100644
--- a/libs/ardour/ardour/region.h
+++ b/libs/ardour/ardour/region.h
@@ -573,6 +573,7 @@ protected:
 	virtual void set_start_internal (timepos_t const &);
 	bool verify_start_and_length (timepos_t const &, timecnt_t&);
 	void first_edit ();
+	virtual void ensure_length_sanity () {}
 
 	void override_opaqueness (bool yn) {
 		_opaque = yn;
diff --git a/libs/ardour/audioregion.cc b/libs/ardour/audioregion.cc
index 4a7e74432e..e90dee6688 100644
--- a/libs/ardour/audioregion.cc
+++ b/libs/ardour/audioregion.cc
@@ -438,6 +438,8 @@ AudioRegion::~AudioRegion ()
 void
 AudioRegion::post_set (const PropertyChange& /*ignored*/)
 {
+	ensure_length_sanity ();
+
 	if (!_sync_marked) {
 		_sync_position = _start;
 	}
@@ -2701,3 +2703,19 @@ AudioRegion::apply_region_fx (BufferSet& bufs, samplepos_t start_sample, samplep
 	_fx_pos = end_sample;
 	_fx_latent_read = false;
 }
+
+void
+AudioRegion::ensure_length_sanity ()
+{
+	if (_type == DataType::AUDIO) {
+		/* Force audio regions to have a length that is the
+		   rounded-down integer number of samples. No other value makes
+		   any sort of logical sense. We tried to fix this at a lower
+		   level, by rounding the return value of
+		   TempoMap::superclock_at(), but the breaks the fundamental
+		   point of a high resolution audio time unit.
+		*/
+		_length = timecnt_t (timepos_t (_length.val().samples()), _length.val().position());
+	}
+}
+
diff --git a/libs/ardour/region.cc b/libs/ardour/region.cc
index 9d6fea03cb..dd2c179d91 100644
--- a/libs/ardour/region.cc
+++ b/libs/ardour/region.cc
@@ -304,6 +304,7 @@ Region::Region (Session& s, timepos_t const & start, timecnt_t const & length, c
 	, _changemap (0)
 {
 	register_properties ();
+	ensure_length_sanity ();
 
 	/* no sources at this point */
 }
@@ -324,6 +325,7 @@ Region::Region (const SourceList& srcs)
 	register_properties ();
 
 	use_sources (srcs);
+	ensure_length_sanity ();
 
 	assert(_sources.size() > 0);
 	assert (_type == srcs.front()->type());
@@ -382,6 +384,7 @@ Region::Region (std::shared_ptr<const Region> other)
 		_sync_position = _start;
 	}
 
+	ensure_length_sanity ();
 	assert (_type == other->data_type());
 }
 
@@ -433,6 +436,7 @@ Region::Region (std::shared_ptr<const Region> other, timecnt_t const & offset)
 		_sync_position = _start;
 	}
 
+	ensure_length_sanity ();
 	assert (_type == other->data_type());
 }
 
@@ -462,6 +466,7 @@ Region::Region (std::shared_ptr<const Region> other, const SourceList& srcs)
 	}
 
 	use_sources (srcs);
+	ensure_length_sanity ();
 	assert(_sources.size() > 0);
 }
 
@@ -567,25 +572,34 @@ Region::set_length_internal (timecnt_t const & len)
 
 	_last_length = timecnt_t (_length.val().distance(), _last_length.position());
 
-	std::shared_ptr<Playlist> pl (playlist());
+	if (_type == DataType::AUDIO) {
 
-	if (pl) {
-		Temporal::TimeDomain td (pl->time_domain());
+		/* Equivalent to what AudioRegion::ensure_length_sanity() does */
+		_length = timecnt_t (timepos_t (len.samples()), _length.val().position());
 
-		/* Note: timecnt_t::time_domain() returns the domain for the
-		 * length component, *not* the position.
-		 */
+	} else {
 
-		if (td != len.time_domain()) {
-			timecnt_t l = _length.val();
-			l.set_time_domain (td);
-			_length = l;
-			return;
+		std::shared_ptr<Playlist> pl (playlist());
+
+		if (pl) {
+			Temporal::TimeDomain td (pl->time_domain());
+
+			/* Note: timecnt_t::time_domain() returns the domain for the
+			 * length component, *not* the position.
+			 */
+
+			if (td != len.time_domain()) {
+				timecnt_t l = _length.val();
+				l.set_time_domain (td);
+				_length = l;
+				return;
+			}
 		}
-	}
-	/* either no playlist or time domain for distance is not changing */
 
-	_length = timecnt_t (len.distance(), _length.val().position());
+		/* either no playlist or time domain for distance is not changing */
+
+		_length = timecnt_t (len.distance(), _length.val().position());
+	}
 }
 
 void