diff --git a/src/tbf_ul.cpp b/src/tbf_ul.cpp
index 489fc87..39e4e95 100644
--- a/src/tbf_ul.cpp
+++ b/src/tbf_ul.cpp
@@ -614,3 +614,8 @@
 		  ws, b->ws_base, pcu_bitcount(ul_slots()), b->ws_pdch);
 	m_window.set_ws(ws);
 }
+
+gprs_rlc_ul_window *gprs_rlcmac_ul_tbf::window()
+{
+	return &m_window;
+}