diff --git a/meson.build b/meson.build
index b27f9f1e1..38483eaf8 100644
--- a/meson.build
+++ b/meson.build
@@ -339,6 +339,7 @@ sources = [
   version_cxx,
   'src/Main.cxx',
   'src/protocol/ArgParser.cxx',
+  'src/protocol/IdleFlags.cxx',
   'src/command/CommandError.cxx',
   'src/command/PositionArg.cxx',
   'src/command/AllCommands.cxx',
@@ -357,7 +358,6 @@ sources = [
   'src/config/PlayerConfig.cxx',
   'src/config/ReplayGainConfig.cxx',
   'src/Idle.cxx',
-  'src/IdleFlags.cxx',
   'src/decoder/Thread.cxx',
   'src/decoder/Control.cxx',
   'src/decoder/Bridge.cxx',
diff --git a/src/Idle.hxx b/src/Idle.hxx
index cb0a369d3..37b7e810e 100644
--- a/src/Idle.hxx
+++ b/src/Idle.hxx
@@ -9,7 +9,7 @@
 #ifndef MPD_IDLE_HXX
 #define MPD_IDLE_HXX
 
-#include "IdleFlags.hxx"
+#include "protocol/IdleFlags.hxx"
 
 /**
  * Adds idle flag (with bitwise "or") and queues notifications to all
diff --git a/src/Instance.cxx b/src/Instance.cxx
index 1f6a424a3..d05b1de14 100644
--- a/src/Instance.cxx
+++ b/src/Instance.cxx
@@ -4,7 +4,7 @@
 #include "config.h"
 #include "Instance.hxx"
 #include "Partition.hxx"
-#include "IdleFlags.hxx"
+#include "protocol/IdleFlags.hxx"
 #include "StateFile.hxx"
 #include "Stats.hxx"
 #include "client/List.hxx"
diff --git a/src/Main.cxx b/src/Main.cxx
index dde5c1342..ba7827bcd 100644
--- a/src/Main.cxx
+++ b/src/Main.cxx
@@ -16,7 +16,7 @@
 #include "command/AllCommands.hxx"
 #include "Partition.hxx"
 #include "tag/Config.hxx"
-#include "IdleFlags.hxx"
+#include "protocol/IdleFlags.hxx"
 #include "Log.hxx"
 #include "LogInit.hxx"
 #include "input/Init.hxx"
diff --git a/src/Partition.cxx b/src/Partition.cxx
index f37dfa6b6..c9d8a7adc 100644
--- a/src/Partition.cxx
+++ b/src/Partition.cxx
@@ -8,7 +8,7 @@
 #include "config/PartitionConfig.hxx"
 #include "lib/fmt/ExceptionFormatter.hxx"
 #include "song/DetachedSong.hxx"
-#include "IdleFlags.hxx"
+#include "protocol/IdleFlags.hxx"
 #include "client/Listener.hxx"
 #include "client/Client.hxx"
 #include "input/cache/Manager.hxx"
diff --git a/src/client/Client.cxx b/src/client/Client.cxx
index f393c6982..90f0c0ab7 100644
--- a/src/client/Client.cxx
+++ b/src/client/Client.cxx
@@ -6,7 +6,7 @@
 #include "Partition.hxx"
 #include "Instance.hxx"
 #include "BackgroundCommand.hxx"
-#include "IdleFlags.hxx"
+#include "protocol/IdleFlags.hxx"
 #include "config.h"
 
 Client::~Client() noexcept
diff --git a/src/client/Subscribe.cxx b/src/client/Subscribe.cxx
index a130ecf54..2b3a8e4a7 100644
--- a/src/client/Subscribe.cxx
+++ b/src/client/Subscribe.cxx
@@ -3,7 +3,7 @@
 
 #include "Client.hxx"
 #include "Partition.hxx"
-#include "IdleFlags.hxx"
+#include "protocol/IdleFlags.hxx"
 
 #include <cassert>
 
diff --git a/src/command/OtherCommands.cxx b/src/command/OtherCommands.cxx
index 2c9451b25..b956b134c 100644
--- a/src/command/OtherCommands.cxx
+++ b/src/command/OtherCommands.cxx
@@ -28,7 +28,7 @@
 #include "client/Response.hxx"
 #include "Partition.hxx"
 #include "Instance.hxx"
-#include "IdleFlags.hxx"
+#include "protocol/IdleFlags.hxx"
 #include "Log.hxx"
 #include "Mapper.hxx"
 
diff --git a/src/command/OutputCommands.cxx b/src/command/OutputCommands.cxx
index 663295ba2..0a917d7a0 100644
--- a/src/command/OutputCommands.cxx
+++ b/src/command/OutputCommands.cxx
@@ -8,7 +8,7 @@
 #include "client/Client.hxx"
 #include "client/Response.hxx"
 #include "Partition.hxx"
-#include "IdleFlags.hxx"
+#include "protocol/IdleFlags.hxx"
 #include "util/CharUtil.hxx"
 #include "util/StringVerify.hxx"
 
diff --git a/src/command/PartitionCommands.cxx b/src/command/PartitionCommands.cxx
index e45316e96..8a2dd112a 100644
--- a/src/command/PartitionCommands.cxx
+++ b/src/command/PartitionCommands.cxx
@@ -5,7 +5,7 @@
 #include "Request.hxx"
 #include "Instance.hxx"
 #include "Partition.hxx"
-#include "IdleFlags.hxx"
+#include "protocol/IdleFlags.hxx"
 #include "output/Filtered.hxx"
 #include "client/Client.hxx"
 #include "client/Response.hxx"
diff --git a/src/command/PlayerCommands.cxx b/src/command/PlayerCommands.cxx
index 0b5a91702..71ce072bf 100644
--- a/src/command/PlayerCommands.cxx
+++ b/src/command/PlayerCommands.cxx
@@ -12,7 +12,7 @@
 #include "client/Response.hxx"
 #include "Partition.hxx"
 #include "Instance.hxx"
-#include "IdleFlags.hxx"
+#include "protocol/IdleFlags.hxx"
 #include "lib/fmt/AudioFormatFormatter.hxx"
 #include "util/StringBuffer.hxx"
 #include "util/ScopeExit.hxx"
diff --git a/src/command/StorageCommands.cxx b/src/command/StorageCommands.cxx
index 239048f99..3cce0eb5c 100644
--- a/src/command/StorageCommands.cxx
+++ b/src/command/StorageCommands.cxx
@@ -16,7 +16,7 @@
 #include "db/plugins/simple/SimpleDatabasePlugin.hxx"
 #include "db/update/Service.hxx"
 #include "TimePrint.hxx"
-#include "IdleFlags.hxx"
+#include "protocol/IdleFlags.hxx"
 
 #include <fmt/format.h>
 
diff --git a/src/output/OutputCommand.cxx b/src/output/OutputCommand.cxx
index aaba87797..d02ad43d5 100644
--- a/src/output/OutputCommand.cxx
+++ b/src/output/OutputCommand.cxx
@@ -13,7 +13,7 @@
 #include "mixer/Mixer.hxx"
 #include "mixer/Memento.hxx"
 #include "mixer/Listener.hxx"
-#include "IdleFlags.hxx"
+#include "protocol/IdleFlags.hxx"
 #include "Partition.hxx"
 
 extern unsigned audio_output_state_version;
diff --git a/src/IdleFlags.cxx b/src/protocol/IdleFlags.cxx
similarity index 96%
rename from src/IdleFlags.cxx
rename to src/protocol/IdleFlags.cxx
index fbcb6e283..ea6bad1d8 100644
--- a/src/IdleFlags.cxx
+++ b/src/protocol/IdleFlags.cxx
@@ -6,7 +6,7 @@
  *
  */
 
-#include "IdleFlags.hxx"
+#include "protocol/IdleFlags.hxx"
 #include "util/ASCII.hxx"
 
 #include <cassert>
diff --git a/src/IdleFlags.hxx b/src/protocol/IdleFlags.hxx
similarity index 100%
rename from src/IdleFlags.hxx
rename to src/protocol/IdleFlags.hxx