diff --git a/gtk2_ardour/ardour_ui_session.cc b/gtk2_ardour/ardour_ui_session.cc
index 298399574d..2c58cbe9fd 100644
--- a/gtk2_ardour/ardour_ui_session.cc
+++ b/gtk2_ardour/ardour_ui_session.cc
@@ -810,7 +810,7 @@ If you still wish to proceed, please use the\n\n\
 					msg.run ();
 					return;
 				}
-				/* fallthrough */
+				[[fallthrough]];
 			case 0:
 				_session->remove_pending_capture_state ();
 				break;
@@ -970,7 +970,7 @@ If you still wish to proceed, please use the\n\n\
 					msg.run ();
 					return;
 				}
-				/* fallthrough */
+				[[fallthrough]];
 			case 0:
 				_session->remove_pending_capture_state ();
 				break;
diff --git a/gtk2_ardour/audio_clock.cc b/gtk2_ardour/audio_clock.cc
index 1488bfe259..88ad93daf6 100644
--- a/gtk2_ardour/audio_clock.cc
+++ b/gtk2_ardour/audio_clock.cc
@@ -489,7 +489,7 @@ AudioClock::end_edit (bool modify)
 			break;
 
 		case Seconds:
-			/* fallthrough */
+			[[fallthrough]];
 		case Samples:
 			if (edit_string.length() < 1) {
 				edit_string = pre_edit_string;
diff --git a/gtk2_ardour/editor.cc b/gtk2_ardour/editor.cc
index 3cbaf81322..d6ed8680d0 100644
--- a/gtk2_ardour/editor.cc
+++ b/gtk2_ardour/editor.cc
@@ -5176,8 +5176,7 @@ Editor::get_preferred_edit_position (EditIgnoreOption ignore, bool from_context_
 				break;
 			}
 		}
-		/* fallthrough */
-
+		[[fallthrough]];
 	default:
 	case EditAtMouse:
 		if (!mouse_sample (ms, ignored)) {
@@ -6840,14 +6839,14 @@ Editor::default_time_domain () const
 
 	switch (_grid_type) {
 		case GridTypeNone:
-			/* fallthrough */
+			[[fallthrough]];
 		case GridTypeMinSec:
-			/* fallthrough */
+			[[fallthrough]];
 		case GridTypeCDFrame:
-			/* fallthrough */
+			[[fallthrough]];
 		case GridTypeTimecode:
-			/* fallthrough */
 			return AudioTime;
+			[[fallthrough]];
 		default:
 			break;
 	}
diff --git a/gtk2_ardour/editor_audio_import.cc b/gtk2_ardour/editor_audio_import.cc
index f7010b098a..180f12db13 100644
--- a/gtk2_ardour/editor_audio_import.cc
+++ b/gtk2_ardour/editor_audio_import.cc
@@ -1073,7 +1073,7 @@ Editor::finish_bringing_in_material (std::shared_ptr<Region> region,
 	}
 
 	case ImportAsTrigger:
-	/* fallthrough */
+	[[fallthrough]];
 	case ImportAsTrack:
 	{
 		if (!existing_track) {
diff --git a/gtk2_ardour/editor_ops.cc b/gtk2_ardour/editor_ops.cc
index 301fd47aaa..0bd71cc022 100644
--- a/gtk2_ardour/editor_ops.cc
+++ b/gtk2_ardour/editor_ops.cc
@@ -2738,7 +2738,7 @@ Editor::cut_copy_section (bool copy)
 			break;
 		case SectionSelectRetainAndMovePlayhead:
 			_session->request_locate (copy ? to_end.samples (): to.samples ());
-			/* fallthough */
+			[[fallthrough]];
 		case SectionSelectRetain:
 			if (!copy || to < end) {
 				selection->set (to, to_end);
diff --git a/gtk2_ardour/marker.cc b/gtk2_ardour/marker.cc
index 83bd5e5aec..373351553f 100644
--- a/gtk2_ardour/marker.cc
+++ b/gtk2_ardour/marker.cc
@@ -190,8 +190,8 @@ ArdourMarker::ArdourMarker (PublicEditor& ed, ArdourCanvas::Item& parent, std::s
 	 */
 
 	switch (_type) {
-	case Mark: /* fallthough */
-	case RegionCue: /* fallthough */
+	case Mark: [[fallthrough]];
+	case RegionCue: [[fallthrough]];
 	case BBTPosition:
 		points = new ArdourCanvas::Points ();
 
@@ -297,13 +297,13 @@ ArdourMarker::ArdourMarker (PublicEditor& ed, ArdourCanvas::Item& parent, std::s
 
 	switch (_type) {
 		case RegionCue:
-			/* fallthrough */
+			[[fallthrough]];
 		case Meter:
-			/* fallthrough */
+			[[fallthrough]];
 		case Tempo:
-			/* fallthrough */
+			[[fallthrough]];
 		case SelectionStart:
-			/* fallthrough */
+			[[fallthrough]];
 		case SelectionEnd:
 			_name_flag = 0;
 			break;
@@ -325,7 +325,7 @@ ArdourMarker::ArdourMarker (PublicEditor& ed, ArdourCanvas::Item& parent, std::s
 
 	switch (_type) {
 		case SelectionStart:
-			/* fallthrough */
+			[[fallthrough]];
 		case SelectionEnd:
 			_pcue->hide();
 			_pmark->show();
diff --git a/gtk2_ardour/meter_patterns.cc b/gtk2_ardour/meter_patterns.cc
index e91b2579a8..6fcd9ff611 100644
--- a/gtk2_ardour/meter_patterns.cc
+++ b/gtk2_ardour/meter_patterns.cc
@@ -516,7 +516,7 @@ meter_render_ticks (Gtk::Widget& w, MeterType type, vector<ARDOUR::DataType> typ
 					points.insert (std::pair<float,float>(  3, 1.0));
 					points.insert (std::pair<float,float>(  4, 0.5));
 					points.insert (std::pair<float,float>(  5, 0.5));
-					/* fallthrough */
+					[[fallthrough]];
 				case MeterPeak0dB:
 					points.insert (std::pair<float,float>(-60, 0.5));
 					points.insert (std::pair<float,float>(-50, 1.0));
@@ -752,12 +752,12 @@ meter_render_metrics (Gtk::Widget& w, MeterType type, vector<DataType> types)
 					points.insert (std::pair<float,string>(  0.0f, "+20"));
 					break;
 				case MeterPeak:
-					/* fallthrough */
+					[[fallthrough]];
 				case MeterKrms:
-					/* fallthrough */
+					[[fallthrough]];
 				default:
 					points.insert (std::pair<float,string>(  3.0f, "+3"));
-					/* fallthrough */
+					[[fallthrough]];
 				case MeterPeak0dB:
 					points.insert (std::pair<float,string>(-50.0f, "-50"));
 					points.insert (std::pair<float,string>(-40.0f, "-40"));
diff --git a/gtk2_ardour/pianokeyboard.cc b/gtk2_ardour/pianokeyboard.cc
index ba5a249917..aaa57c6eb6 100644
--- a/gtk2_ardour/pianokeyboard.cc
+++ b/gtk2_ardour/pianokeyboard.cc
@@ -327,16 +327,16 @@ APianoKeyboard::handle_fixed_keys (GdkEventKey* ev)
 	} else if (ev->type == GDK_KEY_RELEASE) {
 		switch (ev->keyval) {
 			case GDK_KEY_F1:
-				/* fallthrough */
+				[[fallthrough]];
 			case GDK_KEY_F2:
-				/* fallthrough */
+				[[fallthrough]];
 			case GDK_KEY_F3:
-				/* fallthrough */
+				[[fallthrough]];
 			case GDK_KEY_F4:
 				PitchBend (8192, false);
 				break;
 			case GDK_KEY_Up:
-				/* fallthrough */
+				[[fallthrough]];
 			case GDK_KEY_Down:
 				PitchBend (8192, true);
 				return true;
diff --git a/gtk2_ardour/track_record_axis.cc b/gtk2_ardour/track_record_axis.cc
index 14e235e8e6..9a149876aa 100644
--- a/gtk2_ardour/track_record_axis.cc
+++ b/gtk2_ardour/track_record_axis.cc
@@ -615,12 +615,12 @@ TrackRecordAxis::entry_key_press (GdkEventKey* ev)
 {
 	switch (ev->keyval) {
 		case GDK_Escape:
-			/* fallthrough */
+			[[fallthrough]];
 		case GDK_ISO_Left_Tab:
-			/* fallthrough */
+			[[fallthrough]];
 		case GDK_Tab:
-			/* fallthrough */
 			return true;
+			[[fallthrough]];
 		default:
 			break;
 	}
diff --git a/gtk2_ardour/trigger_ui.cc b/gtk2_ardour/trigger_ui.cc
index 98fda9e265..ba9cc36eb8 100644
--- a/gtk2_ardour/trigger_ui.cc
+++ b/gtk2_ardour/trigger_ui.cc
@@ -339,12 +339,12 @@ TriggerUI::entry_key_press (GdkEventKey* ev)
 {
 	switch (ev->keyval) {
 		case GDK_Escape:
-			/* fallthrough */
+			[[fallthrough]];
 		case GDK_ISO_Left_Tab:
-			/* fallthrough */
+			[[fallthrough]];
 		case GDK_Tab:
-			/* fallthrough */
 			return true;
+			[[fallthrough]];
 		default:
 			break;
 	}
diff --git a/gtk2_ardour/vst_plugin_ui.cc b/gtk2_ardour/vst_plugin_ui.cc
index cbdadab8eb..280f8d53d4 100644
--- a/gtk2_ardour/vst_plugin_ui.cc
+++ b/gtk2_ardour/vst_plugin_ui.cc
@@ -231,7 +231,7 @@ VSTPluginUI::dispatch_effeditkey (GdkEventKey* gdk_key)
 			special_key = 15;
 			break;
 		case GDK_Page_Down:
-			/* fallthrough */
+			[[fallthrough]];
 		case GDK_KP_Page_Down:
 			special_key = 16;
 			break;