diff --git a/projects/examples/dev.audio.usm b/projects/examples/dev.audio.usm
index b31c103..57fc83e 100644
--- a/projects/examples/dev.audio.usm
+++ b/projects/examples/dev.audio.usm
@@ -120,7 +120,7 @@ BRK
 
 @play ( pitch -- )
 
-	=Audio.pitch
+	#80 ORA =Audio.pitch
 	,triangle-wave =Audio.wave
 	~track.active =Audio.play
 
@@ -190,7 +190,7 @@ BRK
 	DUP #ff NEQ ^$skip1 JNZ
 		POP ^$listen2 JMP
 	$skip1
-	#00 SWP ,notes ADD2 PEK2 =Audio.pitch
+	#00 SWP ,notes ADD2 PEK2 #80 ORA =Audio.pitch
 	~volume.ch1 =Audio.volume
 	,square-wave =Audio.wave
 	#00 =Audio.play
@@ -200,7 +200,7 @@ BRK
 	DUP #ff NEQ ^$skip2 JNZ
 		POP ^$listen3 JMP
 	$skip2
-	#00 SWP ,notes ADD2 PEK2 =Audio.pitch
+	#00 SWP ,notes ADD2 PEK2 #80 ORA =Audio.pitch
 	~volume.ch2 =Audio.volume
 	,square-wave =Audio.wave
 	#01 =Audio.play
@@ -210,7 +210,7 @@ BRK
 	DUP #ff NEQ ^$skip3 JNZ
 		POP ^$end JMP
 	$skip3
-	#00 SWP ,notes ADD2 PEK2 =Audio.pitch
+	#00 SWP ,notes ADD2 PEK2 #80 ORA =Audio.pitch
 	~volume.ch3 =Audio.volume
 	,triangle-wave =Audio.wave
 	#02 =Audio.play
diff --git a/src/apu.c b/src/apu.c
index 92e40b0..1ef8bf9 100644
--- a/src/apu.c
+++ b/src/apu.c
@@ -78,10 +78,12 @@ apu_render(Apu *apu, Uxn *u, Sint16 *samples, int n_samples)
 }
 
 void
-apu_play_note(Note *note, Uint16 wave_vector, Uint16 envelope_vector, Uint8 volume, Uint8 pitch)
+apu_play_note(Note *note, Uint16 wave_vector, Uint16 envelope_vector, Uint8 volume, Uint8 pitch, Uint8 impl)
 {
 	int i;
+	if(pitch >= 108 || impl == 0) return;
 	note->playing = 1;
+	note->impl = impl;
 	for(i = 0; i < 2; ++i) {
 		note->volume[i] = 0xf & (volume >> 4 * (1 - i));
 		note->wv[i].count = note->wv[i].period = 0;
diff --git a/src/apu.h b/src/apu.h
index 522c9af..a4d033a 100644
--- a/src/apu.h
+++ b/src/apu.h
@@ -29,7 +29,8 @@ typedef struct {
 
 typedef struct {
 	WaveformGenerator wv[2];
-	Sint8 volume[2], playing;
+	Sint8 volume[2];
+	Uint8 playing, impl;
 } Note;
 
 typedef struct {
@@ -40,4 +41,4 @@ typedef struct {
 } Apu;
 
 void apu_render(Apu *apu, Uxn *u, Sint16 *samples, int n_samples);
-void apu_play_note(Note *note, Uint16 wave_vector, Uint16 envelope_vector, Uint8 volume, Uint8 pitch);
+void apu_play_note(Note *note, Uint16 wave_vector, Uint16 envelope_vector, Uint8 volume, Uint8 pitch, Uint8 impl);
diff --git a/src/emulator.c b/src/emulator.c
index 57ca7b4..f95cd3d 100644
--- a/src/emulator.c
+++ b/src/emulator.c
@@ -247,7 +247,7 @@ audio_poke(Uxn *u, Uint16 ptr, Uint8 b0, Uint8 b1)
 	if(b0 == 0xa) {
 		if(b1 >= apu.n_notes) apu.notes = SDL_realloc(apu.notes, (b1 + 1) * sizeof(Note));
 		while(b1 >= apu.n_notes) SDL_zero(apu.notes[apu.n_notes++]);
-		apu_play_note(&apu.notes[b1], (m[0x0] << 8) + m[0x1], (m[0x2] << 8) + m[0x3], m[0x8], m[0x9]);
+		apu_play_note(&apu.notes[b1], (m[0x0] << 8) + m[0x1], (m[0x2] << 8) + m[0x3], m[0x8], m[0x9] & 0x7f, m[0x9] > 0x7f);
 	} else if(b0 == 0xe && apu.queue != NULL) {
 		if(apu.queue->n == apu.queue->sz) {
 			apu.queue->sz = apu.queue->sz < 4 ? 4 : apu.queue->sz * 2;