diff --git a/src/devices/sound/swp00.cpp b/src/devices/sound/swp00.cpp
index c19b7021e84..f94006a1868 100644
--- a/src/devices/sound/swp00.cpp
+++ b/src/devices/sound/swp00.cpp
@@ -99,4 +99,6 @@ void swp00_device::snd_w(offs_t offset, u8 data)
 
 void swp00_device::sound_stream_update(sound_stream &stream, std::vector<read_stream_view> const &inputs, std::vector<write_stream_view> &outputs)
 {
+	outputs[0].fill(0);
+	outputs[1].fill(0);
 }