diff --git a/TODO-RELEASE b/TODO-RELEASE
index 33e27afca..e8fb32be1 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -9,5 +9,6 @@
 #library	what			description / commit summary line
 libosmogsm	new API			gsm0808_create_sapi_reject_cause() with cause argument
 libosmogsm	ABI change		struct osmo_gprs_cell_options size changed (new field at the end)
+libosmogsm	API change		struct ipac_preproc_ave_cfg: new zero-sized flexible array member at end
 libosmovty	ABI change		struct cmd_element: add a field for program specific attributes
 libosmovty	ABI change		struct vty_app_info: optional program specific attributes description
diff --git a/include/osmocom/gsm/protocol/gsm_08_58.h b/include/osmocom/gsm/protocol/gsm_08_58.h
index 046d35859..e9c14e6c3 100644
--- a/include/osmocom/gsm/protocol/gsm_08_58.h
+++ b/include/osmocom/gsm/protocol/gsm_08_58.h
@@ -775,10 +775,12 @@ struct ipac_preproc_ave_cfg {
 		reserved:1;
 	uint8_t h_reqt:5,
 		ave_method:3;
+	uint8_t params[0];
 #elif OSMO_IS_BIG_ENDIAN
 /* auto-generated from the little endian part above (libosmocore/contrib/struct_endianess.py) */
 	uint8_t reserved:1, param_id:2, h_reqave:5;
 	uint8_t ave_method:3, h_reqt:5;
+	uint8_t params[0];
 #endif
 }__attribute__ ((packed));