diff --git a/net/route.go b/net/route.go
index bff99e2d..463f843b 100644
--- a/net/route.go
+++ b/net/route.go
@@ -9,21 +9,13 @@ import (
 
 // A network is considered free if it does not overlap any existing
 // routes on this host. This is the same approach taken by Docker.
-func CheckNetworkFree(subnet *net.IPNet, ignoreIfName string) error {
-	routes, err := netlink.RouteList(nil, netlink.FAMILY_V4)
-	if err != nil {
-		return err
-	}
-	for _, route := range routes {
+func CheckNetworkFree(subnet *net.IPNet, ignoreIfaceNames map[string]struct{}) error {
+	return forEachRoute(ignoreIfaceNames, func(route netlink.Route) error {
 		if route.Dst != nil && overlaps(route.Dst, subnet) {
-			if link, err := netlink.LinkByIndex(route.LinkIndex); err == nil && link.Attrs().Name == ignoreIfName {
-				continue
-			}
-
 			return fmt.Errorf("Network %s overlaps with existing route %s on host.", subnet, route.Dst)
 		}
-	}
-	return nil
+		return nil
+	})
 }
 
 // Two networks overlap if the start-point of one is inside the other.
@@ -33,17 +25,28 @@ func overlaps(n1, n2 *net.IPNet) bool {
 
 // For a specific address, we only care if it is actually *inside* an
 // existing route, because weave-local traffic never hits IP routing.
-func CheckAddressOverlap(addr net.IP, ignoreIfName string) error {
+func CheckAddressOverlap(addr net.IP, ignoreIfaceNames map[string]struct{}) error {
+	return forEachRoute(ignoreIfaceNames, func(route netlink.Route) error {
+		if route.Dst != nil && route.Dst.Contains(addr) {
+			return fmt.Errorf("Address %s overlaps with existing route %s on host.", addr, route.Dst)
+		}
+		return nil
+	})
+}
+
+func forEachRoute(ignoreIfaceNames map[string]struct{}, check func(netlink.Route) error) error {
 	routes, err := netlink.RouteList(nil, netlink.FAMILY_V4)
 	if err != nil {
 		return err
 	}
 	for _, route := range routes {
-		if route.Dst != nil && route.Dst.Contains(addr) {
-			if link, err := netlink.LinkByIndex(route.LinkIndex); err == nil && link.Attrs().Name == ignoreIfName {
+		if link, err := netlink.LinkByIndex(route.LinkIndex); err == nil {
+			if _, found := ignoreIfaceNames[link.Attrs().Name]; found {
 				continue
 			}
-			return fmt.Errorf("Address %s overlaps with existing route %s on host.", addr, route.Dst)
+		}
+		if err := check(route); err != nil {
+			return err
 		}
 	}
 	return nil
diff --git a/prog/netcheck/netcheck.go b/prog/netcheck/netcheck.go
index 78261a0e..fe822f2e 100644
--- a/prog/netcheck/netcheck.go
+++ b/prog/netcheck/netcheck.go
@@ -15,10 +15,21 @@ func fatal(err error) {
 	os.Exit(1)
 }
 
-func main() {
-	var ignoreIfaceName string
+type stringList map[string]struct{}
 
-	mflag.StringVar(&ignoreIfaceName, []string{"-ignore-iface"}, "", "name of interface to ignore)")
+func (ss *stringList) Set(value string) error {
+	(*ss)[value] = struct{}{}
+	return nil
+}
+
+func (ss *stringList) String() string {
+	return fmt.Sprintf("%v", *ss)
+}
+
+func main() {
+	ignoreIfaceNames := make(stringList)
+
+	mflag.Var(&ignoreIfaceNames, []string{"-ignore-iface"}, "name of interface to ignore)")
 	mflag.Parse()
 
 	if len(mflag.Args()) < 1 {
@@ -32,9 +43,9 @@ func main() {
 		fatal(err)
 	}
 	if ipnet.IP.Equal(addr) {
-		err = weavenet.CheckNetworkFree(ipnet, ignoreIfaceName)
+		err = weavenet.CheckNetworkFree(ipnet, ignoreIfaceNames)
 	} else {
-		err = weavenet.CheckAddressOverlap(addr, ignoreIfaceName)
+		err = weavenet.CheckAddressOverlap(addr, ignoreIfaceNames)
 	}
 	if err != nil {
 		fatal(err)