diff --git a/src/tbf.h b/src/tbf.h
index ca5fedf..17ba980 100644
--- a/src/tbf.h
+++ b/src/tbf.h
@@ -326,6 +326,8 @@
 	bool need_control_ts() const;
 	bool have_data() const;
 	int frames_since_last_poll(unsigned fn) const;
+	int frames_since_last_drain(unsigned fn) const;
+	bool keep_open(unsigned fn) const;
 
 	bool is_control_ts(uint8_t ts) const {
 		return ts == control_ts;
@@ -344,6 +346,7 @@
 	uint8_t m_wait_confirm; /* wait for CCCH IMM.ASS cnf */
 	bool m_dl_ack_requested;
 	int32_t m_last_dl_poll_fn;
+	int32_t m_last_dl_drained_fn;
 
 	struct {
 		struct timeval dl_bw_tv; /* timestamp for dl bw calculation */