diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
index e3b0a9d..45c9a8f 100644
--- a/src/tbf_dl.cpp
+++ b/src/tbf_dl.cpp
@@ -969,6 +969,11 @@
 	return lost * 100 / (lost + received);
 }
 
+gprs_rlc_dl_window *gprs_rlcmac_dl_tbf::window()
+{
+	return &m_window;
+}
+
 int gprs_rlcmac_dl_tbf::update_window(unsigned first_bsn,
 	const struct bitvec *rbb)
 {