diff --git a/include/openbsc/trau_frame.h b/include/openbsc/trau_frame.h
index 7f0a2e6..5923d4a 100644
--- a/include/openbsc/trau_frame.h
+++ b/include/openbsc/trau_frame.h
@@ -59,6 +59,7 @@
 int decode_trau_frame(struct decoded_trau_frame *fr, const u_int8_t *trau_bits);
 int encode_trau_frame(u_int8_t *trau_bits, const struct decoded_trau_frame *fr);
 int trau_frame_up2down(struct decoded_trau_frame *fr);
+u_int8_t *trau_idle_frame(void);
 
 
 #endif /* _TRAU_FRAME_H */