diff --git a/Core/BaseFdsChannel.h b/Core/BaseFdsChannel.h
index 07edd2ab..67c75fd9 100644
--- a/Core/BaseFdsChannel.h
+++ b/Core/BaseFdsChannel.h
@@ -29,8 +29,8 @@ public:
 
 	virtual void WriteReg(uint16_t addr, uint8_t value)
 	{
-		switch(addr) {
-			case 0x4080:
+		switch(addr & 0x03) {
+			case 0:
 				_speed = value & 0x3F;
 				_volumeIncrease = (value & 0x40) == 0x40;
 				_envelopeOff = (value & 0x80) == 0x80;
@@ -44,11 +44,11 @@ public:
 				}
 				break;
 
-			case 0x4082:
+			case 2:
 				_frequency = (_frequency & 0x0F00) | value;
 				break;
 
-			case 0x4083:
+			case 3:
 				_frequency = (_frequency & 0xFF) | ((value & 0x0F) << 8);
 				break;
 		}
diff --git a/Core/ModChannel.h b/Core/ModChannel.h
index 7ff2c07f..b9de88fc 100644
--- a/Core/ModChannel.h
+++ b/Core/ModChannel.h
@@ -34,7 +34,7 @@ public:
 				BaseFdsChannel::WriteReg(addr, value);
 				break;
 			case 0x4085:
-				UpdateCounter(_counter & 0x7F);
+				UpdateCounter(value & 0x7F);
 				break;
 			case 0x4087:
 				BaseFdsChannel::WriteReg(addr, value);