diff --git a/src/gprs_bssgp_pcu.cpp b/src/gprs_bssgp_pcu.cpp
index 6c5d72c3..0782dbf9 100644
--- a/src/gprs_bssgp_pcu.cpp
+++ b/src/gprs_bssgp_pcu.cpp
@@ -152,7 +152,7 @@ static int gprs_bssgp_pcu_rx_dl_ud(struct msgb *msg, struct tlv_parsed *tp)
 
 	LOGP(DBSSGP, LOGL_INFO, "LLC [SGSN -> PCU] = TLLI: 0x%08x IMSI: %s len: %d\n", tlli, imsi, len);
 
-	return gprs_rlcmac_tbf::handle(the_pcu.bts, tlli, imsi, ms_class, delay_csec, data, len);
+	return gprs_rlcmac_dl_tbf::handle(the_pcu.bts, tlli, imsi, ms_class, delay_csec, data, len);
 }
 
 int gprs_bssgp_pcu_rx_paging_ps(struct msgb *msg, struct tlv_parsed *tp)
diff --git a/src/tbf.cpp b/src/tbf.cpp
index 7240e1fc..996efa32 100644
--- a/src/tbf.cpp
+++ b/src/tbf.cpp
@@ -196,7 +196,7 @@ static int tbf_new_dl_assignment(struct gprs_rlcmac_bts *bts,
 /**
  * TODO: split into unit test-able parts...
  */
-int gprs_rlcmac_tbf::handle(struct gprs_rlcmac_bts *bts,
+int gprs_rlcmac_dl_tbf::handle(struct gprs_rlcmac_bts *bts,
 		const uint32_t tlli, const char *imsi,
 		const uint8_t ms_class, const uint16_t delay_csec,
 		const uint8_t *data, const uint16_t len)
@@ -1400,7 +1400,7 @@ struct msgb *gprs_rlcmac_tbf::create_ul_ack(uint32_t fn)
 	return msg;
 }
 
-int gprs_rlcmac_tbf::update_window(const uint8_t ssn, const uint8_t *rbb)
+int gprs_rlcmac_dl_tbf::update_window(const uint8_t ssn, const uint8_t *rbb)
 {
 	int16_t dist; /* must be signed */
 	uint16_t lost = 0, received = 0;
@@ -1455,7 +1455,7 @@ int gprs_rlcmac_tbf::update_window(const uint8_t ssn, const uint8_t *rbb)
 }
 
 
-int gprs_rlcmac_tbf::maybe_start_new_window()
+int gprs_rlcmac_dl_tbf::maybe_start_new_window()
 {
 	struct msgb *msg;
 	uint16_t received;
@@ -1781,7 +1781,7 @@ const char *tbf_name(gprs_rlcmac_tbf *tbf)
 }
 
 
-void gprs_rlcmac_tbf::reuse_tbf(const uint8_t *data, const uint16_t len)
+void gprs_rlcmac_dl_tbf::reuse_tbf(const uint8_t *data, const uint16_t len)
 {
 	bts->tbf_reused();
 	m_llc.put_frame(data, len);
@@ -1803,7 +1803,7 @@ void gprs_rlcmac_tbf::reuse_tbf(const uint8_t *data, const uint16_t len)
 	bts->trigger_dl_ass(this, this, NULL);
 }
 
-bool gprs_rlcmac_tbf::dl_window_stalled() const
+bool gprs_rlcmac_dl_tbf::dl_window_stalled() const
 {
 	return dir.dl.window.window_stalled();
 }
diff --git a/src/tbf.h b/src/tbf.h
index 6681836a..e2f3d8f5 100644
--- a/src/tbf.h
+++ b/src/tbf.h
@@ -128,12 +128,6 @@ struct gprs_rlcmac_tbf {
 
 	/* blocks were acked */
 	int rcv_data_block_acknowledged(const uint8_t *data, size_t len, int8_t rssi);
-
-	/* dispatch Unitdata.DL messages */
-	static int handle(struct gprs_rlcmac_bts *bts,
-		const uint32_t tlli, const char *imsi, const uint8_t ms_class,
-		const uint16_t delay_csec, const uint8_t *data, const uint16_t len);
-
 	uint8_t tsc() const;
 
 	int rlcmac_diag();
@@ -260,11 +254,7 @@ struct gprs_rlcmac_tbf {
 	char m_imsi[16];
 
 protected:
-	int update_window(const uint8_t ssn, const uint8_t *rbb);
-	int maybe_start_new_window();
-	void reuse_tbf(const uint8_t *data, const uint16_t len);
 	gprs_rlcmac_bts *bts_data() const;
-	bool dl_window_stalled() const;
 
 	int extract_tlli(const uint8_t *data, const size_t len);
 	void maybe_schedule_uplink_acknack(const rlc_ul_header *rh);
@@ -345,6 +335,11 @@ inline time_t gprs_rlcmac_tbf::created_ts() const
 }
 
 struct gprs_rlcmac_dl_tbf : public gprs_rlcmac_tbf {
+	/* dispatch Unitdata.DL messages */
+	static int handle(struct gprs_rlcmac_bts *bts,
+		const uint32_t tlli, const char *imsi, const uint8_t ms_class,
+		const uint16_t delay_csec, const uint8_t *data, const uint16_t len);
+
 	int append_data(const uint8_t ms_class,
 			const uint16_t pdu_delay_csec,
 			const uint8_t *data, const uint16_t len);
@@ -356,6 +351,10 @@ protected:
 	struct msgb *create_new_bsn(const uint32_t fn, const uint8_t ts);
 	struct msgb *create_dl_acked_block(const uint32_t fn, const uint8_t ts,
 					const int index, const bool fin_first_ack);
+	int update_window(const uint8_t ssn, const uint8_t *rbb);
+	int maybe_start_new_window();
+	bool dl_window_stalled() const;
+	void reuse_tbf(const uint8_t *data, const uint16_t len);
 };
 
 struct gprs_rlcmac_ul_tbf : public gprs_rlcmac_tbf {