diff --git a/TODO.md b/TODO.md
index 52eae1713..45d042792 100644
--- a/TODO.md
+++ b/TODO.md
@@ -5,9 +5,7 @@
   - input pad
   - settings
 - RF5C68 system
-- ZX beeper system
-- Y8950 system
-- maybe YMU759 ADPCM channel
+- ZX beeper system overlay percussion
 - ADPCM chips
 - Game Boy envelope macro/sequence
 - rewrite the system name detection function anyway
diff --git a/src/engine/platform/zxbeeper.h b/src/engine/platform/zxbeeper.h
index 3a8b9ac2c..a91b518b0 100644
--- a/src/engine/platform/zxbeeper.h
+++ b/src/engine/platform/zxbeeper.h
@@ -62,7 +62,7 @@ class DivPlatformZXBeeper: public DivDispatch {
       vol(1),
       outVol(1),
       sPosition(0),
-      duty(3) {}
+      duty(64) {}
   };
   Channel chan[6];
   DivDispatchOscBuffer* oscBuf[6];