diff --git a/dither4.s b/dither4.s
index 276119b..4b44109 100644
--- a/dither4.s
+++ b/dither4.s
@@ -188,11 +188,11 @@ wait_loop:
         sta sample_ptrh
 
         cmp #.hibyte(audio_samples_end)
-        bne audio_cont
+        bmi audio_cont
 
-        ;lda sample_ptrl
-        ;cmp #.lobyte(audio_samples_end)
-        ;bne audio_cont
+        lda sample_ptrl
+        cmp #.lobyte(audio_samples_end)
+        bmi audio_cont
 
         lda #.lobyte(audio_samples)
         sta sample_ptrl
diff --git a/pack-wav.js b/pack-wav.js
index 1bc9cfd..c879448 100644
--- a/pack-wav.js
+++ b/pack-wav.js
@@ -50,6 +50,7 @@ function audio2assembly(audio) {
 audio_samples:
     ${byte2byte(pack(audio))}
 audio_samples_end:
+    .byte 24
 
 `;
 }
@@ -57,7 +58,8 @@ audio_samples_end:
 function wav2assembly(buffer) {
     let wav = new WaveFile(buffer);
     let samples = wav.getSamples();
-    return audio2assembly(samples);
+    let n = samples.length - (samples.length % 131);
+    return audio2assembly(samples.slice(0, n));
 }
 
 let infile = process.argv[2];