diff --git a/src/gsup_server.h b/src/gsup_server.h
index 3d36bff..b52b783 100644
--- a/src/gsup_server.h
+++ b/src/gsup_server.h
@@ -53,4 +53,5 @@
 
 void osmo_gsup_server_destroy(struct osmo_gsup_server *gsups);
 
-void osmo_gsup_configure_wildcard_apn(struct osmo_gsup_message *gsup);
+void osmo_gsup_configure_wildcard_apn(struct osmo_gsup_message *gsup,
+				      uint8_t *apn_buf, size_t apn_buf_size);