diff --git a/src/input/plugins/AlsaInputPlugin.cxx b/src/input/plugins/AlsaInputPlugin.cxx
index 6a98a212e..5a14d43c3 100644
--- a/src/input/plugins/AlsaInputPlugin.cxx
+++ b/src/input/plugins/AlsaInputPlugin.cxx
@@ -62,7 +62,7 @@ class AlsaInputStream final
 	snd_pcm_t *capture_handle;
 	const size_t frame_size;
 
-	AlsaNonBlockPcm non_block;
+	Alsa::NonBlockPcm non_block;
 
 	InjectEvent defer_invalidate_sockets;
 
diff --git a/src/lib/alsa/NonBlock.cxx b/src/lib/alsa/NonBlock.cxx
index a9e8f0506..800bc4886 100644
--- a/src/lib/alsa/NonBlock.cxx
+++ b/src/lib/alsa/NonBlock.cxx
@@ -5,8 +5,10 @@
 #include "Error.hxx"
 #include "event/MultiSocketMonitor.hxx"
 
+namespace Alsa {
+
 Event::Duration
-AlsaNonBlockPcm::PrepareSockets(MultiSocketMonitor &m, snd_pcm_t *pcm)
+NonBlockPcm::PrepareSockets(MultiSocketMonitor &m, snd_pcm_t *pcm)
 {
 	int count = snd_pcm_poll_descriptors_count(pcm);
 	if (count <= 0) {
@@ -31,8 +33,7 @@ AlsaNonBlockPcm::PrepareSockets(MultiSocketMonitor &m, snd_pcm_t *pcm)
 }
 
 void
-AlsaNonBlockPcm::DispatchSockets(MultiSocketMonitor &m,
-				 snd_pcm_t *pcm)
+NonBlockPcm::DispatchSockets(MultiSocketMonitor &m, snd_pcm_t *pcm)
 {
 	int count = snd_pcm_poll_descriptors_count(pcm);
 	if (count <= 0)
@@ -57,7 +58,7 @@ AlsaNonBlockPcm::DispatchSockets(MultiSocketMonitor &m,
 }
 
 Event::Duration
-AlsaNonBlockMixer::PrepareSockets(MultiSocketMonitor &m, snd_mixer_t *mixer) noexcept
+NonBlockMixer::PrepareSockets(MultiSocketMonitor &m, snd_mixer_t *mixer) noexcept
 {
 	int count = snd_mixer_poll_descriptors_count(mixer);
 	if (count <= 0) {
@@ -76,8 +77,7 @@ AlsaNonBlockMixer::PrepareSockets(MultiSocketMonitor &m, snd_mixer_t *mixer) noe
 }
 
 void
-AlsaNonBlockMixer::DispatchSockets(MultiSocketMonitor &m,
-				   snd_mixer_t *mixer) noexcept
+NonBlockMixer::DispatchSockets(MultiSocketMonitor &m, snd_mixer_t *mixer) noexcept
 {
 	int count = snd_mixer_poll_descriptors_count(mixer);
 	if (count <= 0)
@@ -98,3 +98,5 @@ AlsaNonBlockMixer::DispatchSockets(MultiSocketMonitor &m,
 	unsigned short dummy;
 	snd_mixer_poll_descriptors_revents(mixer, pfds, i - pfds, &dummy);
 }
+
+} // namespace Alsa
diff --git a/src/lib/alsa/NonBlock.hxx b/src/lib/alsa/NonBlock.hxx
index 7c8eade59..aae992f50 100644
--- a/src/lib/alsa/NonBlock.hxx
+++ b/src/lib/alsa/NonBlock.hxx
@@ -10,11 +10,13 @@
 
 class MultiSocketMonitor;
 
+namespace Alsa {
+
 /**
  * Helper class for #MultiSocketMonitor's virtual methods which
  * manages the file descriptors for a #snd_pcm_t.
  */
-class AlsaNonBlockPcm {
+class NonBlockPcm {
 	ReusableArray<pollfd> pfd_buffer;
 
 public:
@@ -37,7 +39,7 @@ public:
  * Helper class for #MultiSocketMonitor's virtual methods which
  * manages the file descriptors for a #snd_mixer_t.
  */
-class AlsaNonBlockMixer {
+class NonBlockMixer {
 	ReusableArray<pollfd> pfd_buffer;
 
 public:
@@ -50,3 +52,5 @@ public:
 	 */
 	void DispatchSockets(MultiSocketMonitor &m, snd_mixer_t *mixer) noexcept;
 };
+
+} // namespace Alsa
diff --git a/src/mixer/plugins/AlsaMixerPlugin.cxx b/src/mixer/plugins/AlsaMixerPlugin.cxx
index 25c6b1664..cc849ac30 100644
--- a/src/mixer/plugins/AlsaMixerPlugin.cxx
+++ b/src/mixer/plugins/AlsaMixerPlugin.cxx
@@ -29,7 +29,7 @@ class AlsaMixerMonitor final : MultiSocketMonitor {
 
 	snd_mixer_t *mixer;
 
-	AlsaNonBlockMixer non_block;
+	Alsa::NonBlockMixer non_block;
 
 public:
 	AlsaMixerMonitor(EventLoop &_loop, snd_mixer_t *_mixer) noexcept
diff --git a/src/output/plugins/AlsaOutputPlugin.cxx b/src/output/plugins/AlsaOutputPlugin.cxx
index f1ad85626..a67a91478 100644
--- a/src/output/plugins/AlsaOutputPlugin.cxx
+++ b/src/output/plugins/AlsaOutputPlugin.cxx
@@ -210,7 +210,7 @@ class AlsaOutput final
 	 */
 	std::byte *silence;
 
-	AlsaNonBlockPcm non_block;
+	Alsa::NonBlockPcm non_block;
 
 	/**
 	 * For copying data from OutputThread to IOThread.