diff --git a/libs/ardour/ardour/midi_model.h b/libs/ardour/ardour/midi_model.h
index 6b726775a9..fc08e5a27a 100644
--- a/libs/ardour/ardour/midi_model.h
+++ b/libs/ardour/ardour/midi_model.h
@@ -44,9 +44,12 @@
 #include "evoral/Note.h"
 #include "evoral/Sequence.h"
 
+namespace PBD {
+	class HistoryOwner;
+}
+
 namespace ARDOUR {
 
-class Session;
 class MidiSource;
 class MidiStateTracker;
 
@@ -277,22 +280,22 @@ public:
 	 * This STARTS and COMMITS an undo command.
 	 * The command will constitute one item on the undo stack.
 	 */
-	void apply_diff_command_as_commit (Session& session, PBD::Command* cmd);
+	void apply_diff_command_as_commit (PBD::HistoryOwner&, PBD::Command* cmd);
 
-	void apply_diff_command_as_commit (Session* session, PBD::Command* cmd) { if (session) { apply_diff_command_as_commit (*session, cmd); } }
+	void apply_diff_command_as_commit (PBD::HistoryOwner* history, PBD::Command* cmd) { if (history) { apply_diff_command_as_commit (*history, cmd); } }
 
 	/** Add a command as part of a larger reversible transaction
 	 *
 	 * Ownership of cmd is taken, it must not be deleted by the caller.
 	 * The command will be incorporated into the current command.
 	 */
-	void apply_diff_command_as_subcommand (Session& session, PBD::Command* cmd);
+	void apply_diff_command_as_subcommand (PBD::HistoryOwner&, PBD::Command* cmd);
 
 	/** Apply the midi diff, but without any effect on undo
 	 *
 	 * Ownership of cmd is not changed.
 	 */
-	void apply_diff_command_only (Session& session, PBD::Command* cmd);
+	void apply_diff_command_only (PBD::Command* cmd);
 
 	bool sync_to_source (const Source::WriterLock& source_lock);
 
diff --git a/libs/ardour/import_pt.cc b/libs/ardour/import_pt.cc
index a0a1dd8f0a..85053149d1 100644
--- a/libs/ardour/import_pt.cc
+++ b/libs/ardour/import_pt.cc
@@ -466,7 +466,7 @@ no_audio_tracks:
 			/* PT C-2 = 0, Ardour C-1 = 0, subtract twelve to convert ? */
 			midicmd->add (std::shared_ptr<Evoral::Note<Temporal::Beats> > (new Evoral::Note<Temporal::Beats> ((uint8_t)1, start, len, j->note, j->velocity)));
 		}
-		mm->apply_diff_command_only (*this, midicmd);
+		mm->apply_diff_command_only (midicmd);
 		delete midicmd;
 		std::shared_ptr<Region> copy (RegionFactory::create (mr, true));
 		playlist->clear_changes ();
diff --git a/libs/ardour/luabindings.cc b/libs/ardour/luabindings.cc
index 5595f018d8..76a5fa2e05 100644
--- a/libs/ardour/luabindings.cc
+++ b/libs/ardour/luabindings.cc
@@ -1804,8 +1804,8 @@ LuaBindings::common (lua_State* L)
 		.endClass ()
 
 		.deriveWSPtrClass <MidiModel, AutomatableSequence<Temporal::Beats> > ("MidiModel")
-		.addFunction ("apply_command", (void (MidiModel::*)(Session*, PBD::Command*))&MidiModel::apply_diff_command_as_commit) /* deprecated: left here in case any extant scripts use apply_command */
-		.addFunction ("apply_diff_command_as_commit", (void (MidiModel::*)(Session*, PBD::Command*))&MidiModel::apply_diff_command_as_commit)
+		.addFunction ("apply_command", (void (MidiModel::*)(PBD::HistoryOwner*, PBD::Command*))&MidiModel::apply_diff_command_as_commit) /* deprecated: left here in case any extant scripts use apply_command */
+		.addFunction ("apply_diff_command_as_commit", (void (MidiModel::*)(PBD::HistoryOwner*, PBD::Command*))&MidiModel::apply_diff_command_as_commit)
 		.addFunction ("new_note_diff_command", &MidiModel::new_note_diff_command)
 		.addFunction ("new_sysex_diff_command", &MidiModel::new_sysex_diff_command)
 		.addFunction ("new_patch_change_diff_command", &MidiModel::new_patch_change_diff_command)
diff --git a/libs/ardour/midi_model.cc b/libs/ardour/midi_model.cc
index de4f2f1270..3f69842cf2 100644
--- a/libs/ardour/midi_model.cc
+++ b/libs/ardour/midi_model.cc
@@ -32,6 +32,7 @@
 #include "pbd/compose.h"
 #include "pbd/enumwriter.h"
 #include "pbd/error.h"
+#include "pbd/history_owner.h"
 
 #include "evoral/Control.h"
 
@@ -100,24 +101,24 @@ MidiModel::new_patch_change_diff_command (const string& name)
 
 
 void
-MidiModel::apply_diff_command_as_commit(Session& session, Command* cmd)
+MidiModel::apply_diff_command_as_commit(HistoryOwner& history, Command* cmd)
 {
-	session.begin_reversible_command (cmd->name());
+	history.begin_reversible_command (cmd->name());
 	(*cmd)();
-	session.commit_reversible_command (cmd);
+	history.commit_reversible_command (cmd);
 	set_edited (true);
 }
 
 void
-MidiModel::apply_diff_command_as_subcommand(Session& session, Command* cmd)
+MidiModel::apply_diff_command_as_subcommand (HistoryOwner& history, Command* cmd)
 {
 	(*cmd)();
-	session.add_command (cmd);
+	history.add_command (cmd);
 	set_edited (true);
 }
 
 void
-MidiModel::apply_diff_command_only(Session& session, Command* cmd)
+MidiModel::apply_diff_command_only (Command* cmd)
 {
 	(*cmd)();
 	set_edited (true);