diff --git a/openbsc/include/openbsc/gsm_04_08.h b/openbsc/include/openbsc/gsm_04_08.h
index 3fbc35f..b855aa5 100644
--- a/openbsc/include/openbsc/gsm_04_08.h
+++ b/openbsc/include/openbsc/gsm_04_08.h
@@ -63,5 +63,7 @@
 
 struct msgb *gsm48_create_mm_serv_rej(enum gsm48_reject_value value);
 struct msgb *gsm48_create_loc_upd_rej(uint8_t cause);
+void gsm48_lchan2chan_desc(struct gsm48_chan_desc *cd,
+			   const struct gsm_lchan *lchan);
 
 #endif