diff --git a/include/osmocom/sgsn/gprs_sgsn.h b/include/osmocom/sgsn/gprs_sgsn.h
index 0b721a3..b6afe69 100644
--- a/include/osmocom/sgsn/gprs_sgsn.h
+++ b/include/osmocom/sgsn/gprs_sgsn.h
@@ -459,7 +459,7 @@
 struct sgsn_instance;
 extern const struct value_string *sgsn_auth_state_names;
 
-void sgsn_auth_init(void);
+void sgsn_auth_init(struct sgsn_instance *sgsn);
 struct imsi_acl_entry *sgsn_acl_lookup(const char *imsi, const struct sgsn_config *cfg);
 int sgsn_acl_add(const char *imsi, struct sgsn_config *cfg);
 int sgsn_acl_del(const char *imsi, struct sgsn_config *cfg);