diff --git a/ipam/allocator.go b/ipam/allocator.go
index fa8cfd30..71b21309 100644
--- a/ipam/allocator.go
+++ b/ipam/allocator.go
@@ -77,8 +77,9 @@ type Allocator struct {
 }
 
 type PreClaim struct {
-	Ident string
-	Cidr  address.CIDR
+	Ident       string
+	IsContainer bool
+	Cidr        address.CIDR
 }
 
 type Config struct {
diff --git a/ipam/allocator_test.go b/ipam/allocator_test.go
index 64addc3f..273d7cb1 100644
--- a/ipam/allocator_test.go
+++ b/ipam/allocator_test.go
@@ -174,7 +174,7 @@ func TestAllocatorClaim(t *testing.T) {
 	)
 
 	preAddr, _ := address.ParseCIDR(testPre)
-	allocs, router, subnet := makeNetworkOfAllocators(2, universe, []PreClaim{{container1, preAddr}})
+	allocs, router, subnet := makeNetworkOfAllocators(2, universe, []PreClaim{{container1, true, preAddr}})
 	defer stopNetworkOfAllocators(allocs, router)
 	alloc := allocs[1]
 	addr1, _ := address.ParseCIDR(testAddr1)
diff --git a/prog/weaver/main.go b/prog/weaver/main.go
index b4f7fcc6..f2666188 100644
--- a/prog/weaver/main.go
+++ b/prog/weaver/main.go
@@ -306,15 +306,16 @@ func main() {
 			}
 			trackerName = "awsvpc"
 		}
-		preClaims, err := findExistingAddresses(weavenet.WeaveBridgeName)
+		var allContainerIDs []string
+		if dockerCli != nil {
+			allContainerIDs, err = dockerCli.AllContainerIDs()
+			checkFatal(err)
+		}
+		preClaims, err := findExistingAddresses(dockerCli, allContainerIDs, weavenet.WeaveBridgeName)
 		checkFatal(err)
 		allocator, defaultSubnet = createAllocator(router, ipamConfig, preClaims, db, t, isKnownPeer)
 		observeContainers(allocator)
-		if dockerCli != nil {
-			ids, err := dockerCli.AllContainerIDs()
-			checkFatal(err)
-			allocator.PruneOwned(ids)
-		}
+		allocator.PruneOwned(allContainerIDs)
 	}
 
 	var (
diff --git a/prog/weaver/reclaim.go b/prog/weaver/reclaim.go
index 8678fe8d..5ccae97b 100644
--- a/prog/weaver/reclaim.go
+++ b/prog/weaver/reclaim.go
@@ -3,8 +3,11 @@ package main
 import (
 	"net"
 
+	docker "github.com/fsouza/go-dockerclient"
+
 	"github.com/weaveworks/weave/api"
 	"github.com/weaveworks/weave/common"
+	weavedocker "github.com/weaveworks/weave/common/docker"
 	"github.com/weaveworks/weave/ipam"
 	weavenet "github.com/weaveworks/weave/net"
 	"github.com/weaveworks/weave/net/address"
@@ -17,38 +20,64 @@ func a(cidr *net.IPNet) address.CIDR {
 
 // Get all the existing Weave IPs at startup, so we can stop IPAM
 // giving out any as duplicates
-func findExistingAddresses(bridgeName string) (addrs []ipam.PreClaim, err error) {
+func findExistingAddresses(dockerCli *weavedocker.Client, containerIDs []string, bridgeName string) (addrs []ipam.PreClaim, err error) {
+	Log.Infof("Checking for pre-existing addresses on %s bridge", bridgeName)
 	// First get the address for the bridge
 	bridgeNetDev, err := weavenet.GetBridgeNetDev(bridgeName)
 	if err != nil {
 		return nil, err
 	}
 	for _, cidr := range bridgeNetDev.CIDRs {
+		Log.Infof("%s bridge has address %v", bridgeName, cidr)
 		addrs = append(addrs, ipam.PreClaim{Ident: "weave:expose", Cidr: a(cidr)})
 	}
 
+	add := func(cid string, isContainer bool, netDevs []weavenet.Dev) {
+		for _, netDev := range netDevs {
+			for _, cidr := range netDev.CIDRs {
+				Log.Infof("Found address %v for ID %s", cidr, cid)
+				addrs = append(addrs, ipam.PreClaim{Ident: cid, IsContainer: isContainer, Cidr: a(cidr)})
+			}
+		}
+	}
+
 	// Then find all veths connected to the bridge
 	peerIDs, err := weavenet.ConnectedToBridgeVethPeerIds(bridgeName)
 	if err != nil {
 		return nil, err
 	}
 
-	pids, err := common.AllPids("/proc")
-	if err != nil {
-		return nil, err
-	}
-
-	// Now iterate over all processes to see if they have a network namespace with an attached interface
-	for _, pid := range pids {
-		netDevs, err := weavenet.GetNetDevsByVethPeerIds(pid, peerIDs)
+	// Now iterate over all containers to see if they have a network
+	// namespace with an attached interface
+	if dockerCli != nil {
+		for _, cid := range containerIDs {
+			container, err := dockerCli.InspectContainer(cid)
+			if err != nil {
+				if _, ok := err.(*docker.NoSuchContainer); ok {
+					continue
+				}
+				return nil, err
+			}
+			if container.State.Pid != 0 {
+				netDevs, err := weavenet.GetNetDevsByVethPeerIds(container.State.Pid, peerIDs)
+				if err != nil {
+					return nil, err
+				}
+				add(cid, true, netDevs)
+			}
+		}
+	} else {
+		// If we don't have a Docker connection, iterate over all processes
+		pids, err := common.AllPids("/proc")
 		if err != nil {
 			return nil, err
 		}
-		for _, netDev := range netDevs {
-			for _, cidr := range netDev.CIDRs {
-				// We don't know the container ID, so use special magic string
-				addrs = append(addrs, ipam.PreClaim{Ident: api.NoContainerID, Cidr: a(cidr)})
+		for _, pid := range pids {
+			netDevs, err := weavenet.GetNetDevsByVethPeerIds(pid, peerIDs)
+			if err != nil {
+				return nil, err
 			}
+			add(api.NoContainerID, false, netDevs)
 		}
 	}
 	return addrs, nil