diff --git a/meson.build b/meson.build
index b5548733b..813323ff0 100644
--- a/meson.build
+++ b/meson.build
@@ -206,6 +206,7 @@ sources = [
   'src/decoder/DecoderPrint.cxx',
   'src/client/Listener.cxx',
   'src/client/Client.cxx',
+  'src/client/Domain.cxx',
   'src/client/Event.cxx',
   'src/client/Expire.cxx',
   'src/client/Global.cxx',
diff --git a/src/client/Client.cxx b/src/client/Client.cxx
index c141edf3c..2bb326bf8 100644
--- a/src/client/Client.cxx
+++ b/src/client/Client.cxx
@@ -17,14 +17,12 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include "Internal.hxx"
+#include "Client.hxx"
 #include "Partition.hxx"
 #include "Instance.hxx"
 #include "util/Domain.hxx"
 #include "config.h"
 
-const Domain client_domain("client");
-
 Client::~Client() noexcept
 {
 	if (FullyBufferedSocket::IsDefined())
diff --git a/src/client/Domain.cxx b/src/client/Domain.cxx
new file mode 100644
index 000000000..7487cf1a1
--- /dev/null
+++ b/src/client/Domain.cxx
@@ -0,0 +1,23 @@
+/*
+ * Copyright 2003-2019 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "Domain.hxx"
+#include "util/Domain.hxx"
+
+const Domain client_domain("client");
diff --git a/src/client/Domain.hxx b/src/client/Domain.hxx
new file mode 100644
index 000000000..6c050c835
--- /dev/null
+++ b/src/client/Domain.hxx
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2003-2019 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_CLIENT_DOMAIN_HXX
+#define MPD_CLIENT_DOMAIN_HXX
+
+extern const class Domain client_domain;
+
+#endif
diff --git a/src/client/Expire.cxx b/src/client/Expire.cxx
index 32adf5d54..3f6e57f6e 100644
--- a/src/client/Expire.cxx
+++ b/src/client/Expire.cxx
@@ -17,7 +17,8 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include "Internal.hxx"
+#include "Client.hxx"
+#include "Domain.hxx"
 #include "Log.hxx"
 
 void
diff --git a/src/client/Internal.hxx b/src/client/Internal.hxx
index f9555e0cf..ff05e2a79 100644
--- a/src/client/Internal.hxx
+++ b/src/client/Internal.hxx
@@ -27,8 +27,6 @@
 static constexpr unsigned CLIENT_MAX_SUBSCRIPTIONS = 16;
 static constexpr unsigned CLIENT_MAX_MESSAGES = 64;
 
-extern const class Domain client_domain;
-
 extern std::chrono::steady_clock::duration client_timeout;
 extern size_t client_max_command_list_size;
 extern size_t client_max_output_buffer_size;
diff --git a/src/client/New.cxx b/src/client/New.cxx
index 6ee1eeedb..5c21d2a7c 100644
--- a/src/client/New.cxx
+++ b/src/client/New.cxx
@@ -19,6 +19,7 @@
 
 #include "config.h"
 #include "Internal.hxx"
+#include "Domain.hxx"
 #include "List.hxx"
 #include "Partition.hxx"
 #include "Instance.hxx"
diff --git a/src/client/Process.cxx b/src/client/Process.cxx
index 1f37d6a91..f0820918c 100644
--- a/src/client/Process.cxx
+++ b/src/client/Process.cxx
@@ -18,6 +18,7 @@
  */
 
 #include "Internal.hxx"
+#include "Domain.hxx"
 #include "protocol/Result.hxx"
 #include "command/AllCommands.hxx"
 #include "Log.hxx"