diff --git a/src/modem-manager/nm-modem.c b/src/modem-manager/nm-modem.c
index 1596472602..487b1c49bb 100644
--- a/src/modem-manager/nm-modem.c
+++ b/src/modem-manager/nm-modem.c
@@ -545,8 +545,7 @@ deactivate (NMModem *self, NMDevice *device)
 	case MM_MODEM_IP_METHOD_DHCP:
 		ifindex = nm_device_get_ip_ifindex (device);
 		if (ifindex > 0) {
-			/* FIXME: use AF_UNSPEC here when we have IPv6 support */
-			nm_system_iface_flush_routes (ifindex, AF_INET);
+			nm_system_iface_flush_routes (ifindex, AF_UNSPEC);
 			nm_system_iface_flush_addresses (ifindex, AF_UNSPEC);
 			nm_system_iface_set_up (ifindex, FALSE, NULL);
 		}