diff --git a/src/mixer/MixerAll.cxx b/src/mixer/MixerAll.cxx
index cb035d0cc..f652a9a95 100644
--- a/src/mixer/MixerAll.cxx
+++ b/src/mixer/MixerAll.cxx
@@ -149,7 +149,8 @@ MultipleOutputs::SetSoftwareVolume(unsigned volume)
 		const auto mixer = ao->mixer;
 
 		if (mixer != nullptr &&
-		    &mixer->plugin == &software_mixer_plugin)
+		    (&mixer->plugin == &software_mixer_plugin ||
+		     &mixer->plugin == &null_mixer_plugin))
 			mixer_set_volume(mixer, volume, IgnoreError());
 	}
 }