diff --git a/libnm/nm-vpn-plugin-old.c b/libnm/nm-vpn-plugin-old.c
index b0334febcb..59ea65b413 100644
--- a/libnm/nm-vpn-plugin-old.c
+++ b/libnm/nm-vpn-plugin-old.c
@@ -480,7 +480,7 @@ impl_vpn_plugin_old_need_secrets (NMVpnPluginOld *plugin,
                                   gpointer user_data)
 {
 	NMConnection *connection;
-	char *setting_name;
+	const char *setting_name;
 	gboolean needed;
 	GError *error = NULL;
 
@@ -511,7 +511,6 @@ impl_vpn_plugin_old_need_secrets (NMVpnPluginOld *plugin,
 		g_assert (setting_name);
 		g_dbus_method_invocation_return_value (context,
 		                                       g_variant_new ("(s)", setting_name));
-		g_free (setting_name);
 	} else {
 		/* No secrets required */
 		g_dbus_method_invocation_return_value (context,
diff --git a/libnm/nm-vpn-plugin-old.h b/libnm/nm-vpn-plugin-old.h
index 7fcc1c1c0a..af8f4ff61b 100644
--- a/libnm/nm-vpn-plugin-old.h
+++ b/libnm/nm-vpn-plugin-old.h
@@ -73,7 +73,7 @@ typedef struct {
 
 	gboolean (*need_secrets) (NMVpnPluginOld *plugin,
 	                          NMConnection *connection,
-	                          char **setting_name,
+	                          const char **setting_name,
 	                          GError **error);
 
 	gboolean (*disconnect)   (NMVpnPluginOld   *plugin,