diff --git a/net/if.go b/net/if.go
index 9cea43bc..3cf3baab 100644
--- a/net/if.go
+++ b/net/if.go
@@ -2,6 +2,7 @@ package net
 
 import (
 	"fmt"
+	"math"
 	"net"
 	"time"
 )
@@ -10,11 +11,17 @@ const (
 	sleepTime = 100 * time.Millisecond
 )
 
+// Wait `wait` seconds for an interface to come up. Pass zero to check once
+// and return immediately, or a negative value to wait indefinitely.
 func EnsureInterface(ifaceName string, wait int) (iface *net.Interface, err error) {
 	if iface, err = findInterface(ifaceName); err == nil || wait == 0 {
 		return
 	}
-	for i := time.Duration(wait) * time.Second / sleepTime; err != nil && i > 0; i-- {
+	i := int64(math.MaxInt64)
+	if wait > 0 {
+		i = int64(time.Duration(wait) * time.Second / sleepTime)
+	}
+	for ; err != nil && i > 0; i-- {
 		time.Sleep(sleepTime)
 		iface, err = findInterface(ifaceName)
 	}
diff --git a/prog/weavedns/Dockerfile b/prog/weavedns/Dockerfile
index d7af8837..883b34b8 100644
--- a/prog/weavedns/Dockerfile
+++ b/prog/weavedns/Dockerfile
@@ -3,4 +3,4 @@ MAINTAINER Weaveworks Inc <help@weave.works>
 WORKDIR /home/weave
 ADD ./weavedns /home/weave/
 EXPOSE 53/udp
-ENTRYPOINT ["/home/weave/weavedns", "-wait", "20"]
+ENTRYPOINT ["/home/weave/weavedns"]
diff --git a/prog/weavedns/main.go b/prog/weavedns/main.go
index 21193da6..69832eaf 100644
--- a/prog/weavedns/main.go
+++ b/prog/weavedns/main.go
@@ -46,7 +46,7 @@ func main() {
 	flag.StringVar(&ifaceName, "iface", "", "name of interface to use for multicast")
 	flag.StringVar(&apiPath, "api", "unix:///var/run/docker.sock", "path to Docker API socket")
 	flag.StringVar(&domain, "domain", weavedns.DefaultLocalDomain, "local domain (ie, 'weave.local.')")
-	flag.IntVar(&wait, "wait", 0, "number of seconds to wait for interface to be created and come up")
+	flag.IntVar(&wait, "wait", -1, "number of seconds to wait for interfaces to come up (0=don't wait, -1=wait forever)")
 	flag.IntVar(&dnsPort, "dnsport", weavedns.DefaultServerPort, "port to listen to DNS requests")
 	flag.StringVar(&httpIfaceName, "httpiface", "", "interface on which to listen for HTTP requests (defaults to empty string which listens on all interfaces)")
 	flag.IntVar(&httpPort, "httpport", weavedns.DefaultHTTPPort, "port to listen to HTTP requests")
diff --git a/prog/weaver/Dockerfile b/prog/weaver/Dockerfile
index 437fc9e0..e91764e0 100644
--- a/prog/weaver/Dockerfile
+++ b/prog/weaver/Dockerfile
@@ -2,4 +2,4 @@ FROM scratch
 MAINTAINER Weaveworks Inc <help@weave.works>
 WORKDIR /home/weave
 ADD ./weaver /home/weave/
-ENTRYPOINT ["/home/weave/weaver", "-wait", "20"]
+ENTRYPOINT ["/home/weave/weaver"]
diff --git a/prog/weaver/main.go b/prog/weaver/main.go
index d0ac8596..c17a7d46 100644
--- a/prog/weaver/main.go
+++ b/prog/weaver/main.go
@@ -64,7 +64,7 @@ func main() {
 	flag.StringVar(&routerName, "name", "", "name of router (defaults to MAC of interface)")
 	flag.StringVar(&nickName, "nickname", "", "nickname of peer (defaults to hostname)")
 	flag.StringVar(&password, "password", "", "network password")
-	flag.IntVar(&wait, "wait", 0, "number of seconds to wait for interface to be created and come up (0 = don't wait)")
+	flag.IntVar(&wait, "wait", -1, "number of seconds to wait for interface to come up (0=don't wait, -1=wait forever)")
 	flag.BoolVar(&debug, "debug", false, "enable debug logging")
 	flag.BoolVar(&pktdebug, "pktdebug", false, "enable per-packet debug logging")
 	flag.StringVar(&prof, "profile", "", "enable profiling and write profiles to given path")
diff --git a/prog/weavewait/main.go b/prog/weavewait/main.go
index 3cb78663..0acd5f74 100644
--- a/prog/weavewait/main.go
+++ b/prog/weavewait/main.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"math"
 	"os"
 	"os/exec"
 	"os/signal"
@@ -17,20 +18,19 @@ func main() {
 	}
 
 	args := os.Args[1:]
-	signalWait := 20
+	signalWait := time.Duration(math.MaxInt64)
 	if args[0] == "-s" {
 		signalWait = 0
 		args = args[1:]
 	}
-	interfaceWait := 20 - signalWait
 
 	usr2 := make(chan os.Signal)
 	signal.Notify(usr2, syscall.SIGUSR2)
 	select {
 	case <-usr2:
-	case <-time.After(time.Duration(signalWait) * time.Second):
+	case <-time.After(signalWait):
 	}
-	_, err := net.EnsureInterface("ethwe", interfaceWait)
+	_, err := net.EnsureInterface("ethwe", -1)
 	checkErr(err)
 
 	binary, err := exec.LookPath(args[0])