diff --git a/openbsc/src/gprs/gb_proxy_vty.c b/openbsc/src/gprs/gb_proxy_vty.c
index 29494c6..d40d9b3 100644
--- a/openbsc/src/gprs/gb_proxy_vty.c
+++ b/openbsc/src/gprs/gb_proxy_vty.c
@@ -230,7 +230,7 @@
 		g_cfg->core_apn =
 			talloc_realloc_size(NULL, g_cfg->core_apn, apn_len + 1);
 		g_cfg->core_apn_size =
-			gprs_str_to_apn(g_cfg->core_apn, apn, apn_len + 1);
+			gprs_str_to_apn(g_cfg->core_apn, apn_len + 1, apn);
 	}
 
 	return CMD_SUCCESS;