diff --git a/pipewire-jack/src/metadata.c b/pipewire-jack/src/metadata.c
index 668a2b5b3..309bc04c8 100644
--- a/pipewire-jack/src/metadata.c
+++ b/pipewire-jack/src/metadata.c
@@ -363,15 +363,15 @@ int jack_set_property_change_callback (jack_client_t*             client,
 	return 0;
 }
 
-SPA_EXPORT
-const char* JACK_METADATA_PRETTY_NAME = "http://jackaudio.org/metadata/pretty-name";
-SPA_EXPORT
-const char* JACK_METADATA_HARDWARE = "http://jackaudio.org/metadata/hardware";
-SPA_EXPORT
-const char* JACK_METADATA_CONNECTED = "http://jackaudio.org/metadata/connected";
-SPA_EXPORT
-const char* JACK_METADATA_PORT_GROUP = "http://jackaudio.org/metadata/port-group";
-SPA_EXPORT
-const char* JACK_METADATA_ICON_SMALL = "http://jackaudio.org/metadata/icon-small";
-SPA_EXPORT
-const char* JACK_METADATA_ICON_LARGE = "http://jackaudio.org/metadata/icon-large";
+#define JACK_METADATA_PREFIX "http://jackaudio.org/metadata/"
+SPA_EXPORT const char* JACK_METADATA_CONNECTED   = JACK_METADATA_PREFIX "connected";
+SPA_EXPORT const char* JACK_METADATA_EVENT_TYPES = JACK_METADATA_PREFIX "event-types";
+SPA_EXPORT const char* JACK_METADATA_HARDWARE    = JACK_METADATA_PREFIX "hardware";
+SPA_EXPORT const char* JACK_METADATA_ICON_LARGE  = JACK_METADATA_PREFIX "icon-large";
+SPA_EXPORT const char* JACK_METADATA_ICON_NAME   = JACK_METADATA_PREFIX "icon-name";
+SPA_EXPORT const char* JACK_METADATA_ICON_SMALL  = JACK_METADATA_PREFIX "icon-small";
+SPA_EXPORT const char* JACK_METADATA_ORDER       = JACK_METADATA_PREFIX "order";
+SPA_EXPORT const char* JACK_METADATA_PORT_GROUP  = JACK_METADATA_PREFIX "port-group";
+SPA_EXPORT const char* JACK_METADATA_PRETTY_NAME = JACK_METADATA_PREFIX "pretty-name";
+SPA_EXPORT const char* JACK_METADATA_SIGNAL_TYPE = JACK_METADATA_PREFIX "signal-type";
+#undef JACK_METADATA_PREFIX