diff --git a/libweston/weston-log-internal.h b/libweston/weston-log-internal.h
index 222a751b..6e28a4f5 100644
--- a/libweston/weston-log-internal.h
+++ b/libweston/weston-log-internal.h
@@ -102,4 +102,10 @@ weston_vlog(const char *fmt, va_list ap);
 int
 weston_vlog_continue(const char *fmt, va_list ap);
 
+void *
+weston_log_subscription_get_data(struct weston_log_subscription *sub);
+
+void
+weston_log_subscription_set_data(struct weston_log_subscription *sub, void *data);
+
 #endif /* WESTON_LOG_INTERNAL_H */
diff --git a/libweston/weston-log.c b/libweston/weston-log.c
index 1021ebb2..de5220e1 100644
--- a/libweston/weston-log.c
+++ b/libweston/weston-log.c
@@ -113,6 +113,8 @@ struct weston_log_subscription {
 	struct weston_log_scope *source;
 	struct wl_list source_link;     /**< weston_log_scope::subscription_list  or
 					  weston_log_context::pending_subscription_list */
+
+	void *data;
 };
 
 static struct weston_log_subscription *
@@ -208,6 +210,20 @@ weston_log_subscription_vprintf(struct weston_log_subscription *sub,
 	}
 }
 
+void
+weston_log_subscription_set_data(struct weston_log_subscription *sub, void *data)
+{
+	/* don't allow data to already be set */
+	assert(!sub->data);
+	sub->data = data;
+}
+
+void *
+weston_log_subscription_get_data(struct weston_log_subscription *sub)
+{
+	return sub->data;
+}
+
 /** Creates a new subscription using the subscriber by \c owner.
  *
  * The subscription created is added to the \c owner subscription list.