--- a/src/mpdcli.hxx
+++ b/src/mpdcli.hxx
@@ -87,7 +87,8 @@
 public:
     MPDCli(const std::string& host, int port = 6600, 
            const std::string& pass="", const std::string& m_onstart="",
-           const std::string& m_onstop="");
+           const std::string& m_onstop="",
+           const std::string& m_onvolumechange="");
     ~MPDCli();
     bool ok() {return m_ok && m_conn;}
     bool setVolume(int ivol, bool isMute = false);
@@ -137,6 +138,7 @@
     std::string m_password;
     std::string m_onstart;
     std::string m_onstop;
+    std::string m_onvolumechange;
     regex_t m_tpuexpr;
     // addtagid command only exists for mpd 0.19 and later.
     bool m_have_addtagid;