diff --git a/src/mixer/plugins/OssMixerPlugin.cxx b/src/mixer/plugins/OssMixerPlugin.cxx
index 52d1795ad..a84188d03 100644
--- a/src/mixer/plugins/OssMixerPlugin.cxx
+++ b/src/mixer/plugins/OssMixerPlugin.cxx
@@ -175,7 +175,7 @@ OssMixer::SetVolume(unsigned volume)
 		throw MakeErrno("failed to set OSS volume");
 }
 
-const MixerPlugin oss_mixer_plugin = {
+constexpr MixerPlugin oss_mixer_plugin = {
 	oss_mixer_init,
 	true,
 };
diff --git a/src/mixer/plugins/SndioMixerPlugin.cxx b/src/mixer/plugins/SndioMixerPlugin.cxx
index d9776c02d..f55691833 100644
--- a/src/mixer/plugins/SndioMixerPlugin.cxx
+++ b/src/mixer/plugins/SndioMixerPlugin.cxx
@@ -53,7 +53,7 @@ sndio_mixer_init([[maybe_unused]] EventLoop &event_loop,
 	return new SndioMixer((SndioOutput &)ao, listener);
 }
 
-const MixerPlugin sndio_mixer_plugin = {
+constexpr MixerPlugin sndio_mixer_plugin = {
 	sndio_mixer_init,
 	false,
 };
diff --git a/src/output/plugins/OssOutputPlugin.cxx b/src/output/plugins/OssOutputPlugin.cxx
index 13dbcbcbe..4ed79e52f 100644
--- a/src/output/plugins/OssOutputPlugin.cxx
+++ b/src/output/plugins/OssOutputPlugin.cxx
@@ -634,7 +634,7 @@ OssOutput::Play(const void *chunk, size_t size)
 	}
 }
 
-const struct AudioOutputPlugin oss_output_plugin = {
+constexpr struct AudioOutputPlugin oss_output_plugin = {
 	"oss",
 	oss_output_test_default_device,
 	OssOutput::Create,
diff --git a/src/output/plugins/SndioOutputPlugin.cxx b/src/output/plugins/SndioOutputPlugin.cxx
index 4221099fc..cd284d401 100644
--- a/src/output/plugins/SndioOutputPlugin.cxx
+++ b/src/output/plugins/SndioOutputPlugin.cxx
@@ -185,7 +185,7 @@ SndioOutput::RegisterMixerListener(Mixer *_mixer, MixerListener *_listener) {
 	listener = _listener;
 }
 
-const struct AudioOutputPlugin sndio_output_plugin = {
+constexpr struct AudioOutputPlugin sndio_output_plugin = {
 	"sndio",
 	sndio_test_default_device,
 	SndioOutput::Create,