diff --git a/midi2cv/part.h b/midi2cv/part.h
index b300926..4187290 100644
--- a/midi2cv/part.h
+++ b/midi2cv/part.h
@@ -5,18 +5,14 @@
 
 #define TOTAL_COLUMN_COUNT 4
 
-typedef enum { MIDI_THRU_OFF,
-  MIDI_THRU_ON,
-  MIDI_THRU_POLYCHAIN } MIDIThruMode_t;
+typedef enum { MIDI_THRU_OFF = 0,
+  MIDI_THRU_ON = 1,
+  MIDI_THRU_POLYCHAIN = 2 } MIDIThruMode_t;
 
 typedef enum {
   BI_OFF = 0,
   BI_PITCH_UNI,
-  BI_PITCH_BI,
-  BI_SAWTOOTH,
-  BI_SQUARE,
-  BI_SINE,
-  BI_TRIANGLE
+  BI_PITCH_BI
 } BiOutputType_t;
 
 typedef enum {
@@ -44,10 +40,10 @@ typedef enum {
 } PartVoiceCount_t;
 
 typedef enum {
-  VOICE_DETAIL_S,
-  VOICE_DETAIL_M,
-  VOICE_DETAIL_L,
-  VOICE_DETAIL_XL
+  VOICE_DETAIL_S = 0,
+  VOICE_DETAIL_M = 1,
+  VOICE_DETAIL_L = 2,
+  VOICE_DETAIL_XL = 3
 } PartVoiceDetail_t;
 
 class Part {
diff --git a/midi2cv/ui/part_menu.cc b/midi2cv/ui/part_menu.cc
index 948fb48..cfcf1fb 100644
--- a/midi2cv/ui/part_menu.cc
+++ b/midi2cv/ui/part_menu.cc
@@ -8,6 +8,7 @@ static const char* kMidiChannelStrings[] = { "omni", "1", "2", "3", "4", "5", "6
   "7", "8", "9", "10", "11", "12", "13",
   "14", "15", "16" };
 static const char* kMidiInputStrings[] = { "omni", "usb", "midi" };
+static const char* kMidiThruStrings[] = {"off", "on", "polychain"};
 
 PartMenu::PartMenu()
     : item_voice_count("voice count", 1, 1, 4, 1)
@@ -17,6 +18,7 @@ PartMenu::PartMenu()
     , item_midi_input("MIDI input", 0, kMidiInputStrings, 3)
     , item_midi_lowest_note("MIDI lowest", 0)
     , item_midi_highest_note("MIDI highest", 127)
+    , item_midi_thru_mode("MIDI thru", 0, kMidiThruStrings, 3)
 {
   this->menu.add_item(&this->item_voice_count);
   this->menu.add_item(&this->item_voice_detail);
@@ -25,6 +27,7 @@ PartMenu::PartMenu()
   this->menu.add_item(&this->item_midi_input);
   this->menu.add_item(&this->item_midi_lowest_note);
   this->menu.add_item(&this->item_midi_highest_note);
+  this->menu.add_item(&this->item_midi_thru_mode);
 }
 
 void PartMenu::up()
diff --git a/midi2cv/ui/part_menu.h b/midi2cv/ui/part_menu.h
index ff5eb6f..a7115bc 100644
--- a/midi2cv/ui/part_menu.h
+++ b/midi2cv/ui/part_menu.h
@@ -24,4 +24,5 @@ class PartMenu {
   StringListMenuItem item_midi_input;
   MidiNoteMenuItem item_midi_lowest_note;
   MidiNoteMenuItem item_midi_highest_note;
+  StringListMenuItem item_midi_thru_mode;
 };