diff --git a/openbsc/include/openbsc/gsm_data_shared.h b/openbsc/include/openbsc/gsm_data_shared.h
index 6fb63f9..ad9b63f 100644
--- a/openbsc/include/openbsc/gsm_data_shared.h
+++ b/openbsc/include/openbsc/gsm_data_shared.h
@@ -254,6 +254,7 @@
 	} tch;
 	/* BTS-side ciphering state (rx only, bi-directional, ...) */
 	uint8_t ciph_state;
+	uint8_t loopback;
 #endif
 };