diff --git a/ipam/allocator.go b/ipam/allocator.go
index b3951db0..625646ff 100644
--- a/ipam/allocator.go
+++ b/ipam/allocator.go
@@ -115,7 +115,20 @@ func NewAllocator(config Config) *Allocator {
 
 // Start runs the allocator goroutine
 func (alloc *Allocator) Start() {
-	alloc.loadPersistedData()
+	loadedPersistedData := alloc.loadPersistedData()
+	switch {
+	case loadedPersistedData && len(alloc.seed) != 0:
+		alloc.infof("Found persisted IPAM data, ignoring supplied IPAM seed")
+	case loadedPersistedData:
+		alloc.infof("Initialising with persisted data")
+	case len(alloc.seed) != 0:
+		alloc.infof("Initialising with supplied IPAM seed")
+		alloc.createRing(alloc.seed)
+	case alloc.paxos.IsElector():
+		alloc.infof("Initialising via deferred consensus")
+	default:
+		alloc.infof("Initialising as observer - awaiting IPAM data from another peer")
+	}
 	actionChan := make(chan func(), mesh.ChannelSize)
 	stopChan := make(chan struct{})
 	alloc.actionChan = actionChan
@@ -890,52 +903,57 @@ func (alloc *Allocator) persistRing() {
 	}
 }
 
-func (alloc *Allocator) loadPersistedData() {
+// Returns true if persisted data is to be used, otherwise false
+func (alloc *Allocator) loadPersistedData() bool {
 	var checkPeerName mesh.PeerName
 	nameFound, err := alloc.db.Load(nameIdent, &checkPeerName)
 	if err != nil {
 		alloc.fatalf("Error loading persisted peer name: %s", err)
 	}
-	ringFound, err := alloc.db.Load(ringIdent, &alloc.ring)
+	var persistedRing *ring.Ring
+	ringFound, err := alloc.db.Load(ringIdent, &persistedRing)
 	if err != nil {
 		alloc.fatalf("Error loading persisted IPAM data: %s", err)
 	}
-	ownedFound, err := alloc.db.Load(ownedIdent, &alloc.owned)
+	var persistedOwned map[string]ownedData
+	ownedFound, err := alloc.db.Load(ownedIdent, &persistedOwned)
 	if err != nil {
 		alloc.fatalf("Error loading persisted address data: %s", err)
 	}
 
-	if nameFound {
-		if checkPeerName == alloc.ourName {
-			if ringFound {
-				if len(alloc.seed) != 0 {
-					alloc.infof("Found persisted IPAM data, ignoring supplied IPAM seed")
-				}
-				alloc.space.UpdateRanges(alloc.ring.OwnedRanges())
-			}
-			if ownedFound {
-				for _, d := range alloc.owned {
-					for _, cidr := range d.Cidrs {
-						alloc.space.Claim(cidr.Addr)
-					}
-				}
-			}
-			return
-		}
-		alloc.infof("Deleting persisted data for peername %s", checkPeerName)
+	overwritePersisted := func(fmt string, args ...interface{}) {
+		alloc.infof(fmt, args...)
 		alloc.persistRing()
 		alloc.persistOwned()
 	}
 
-	if len(alloc.seed) != 0 {
-		alloc.infof("Initialising with supplied IPAM seed")
-		alloc.createRing(alloc.seed)
-	} else if alloc.paxos.IsElector() {
-		alloc.infof("Initialising via deferred consensus")
-	} else {
-		alloc.infof("Initialising as observer - awaiting IPAM data from another peer")
+	if !nameFound || !ringFound {
+		overwritePersisted("No valid persisted data")
+		return false
 	}
 
+	if checkPeerName != alloc.ourName {
+		overwritePersisted("Deleting persisted data for peername %s", checkPeerName)
+		return false
+	}
+
+	if persistedRing.Range() != alloc.universe {
+		overwritePersisted("Deleting persisted data for IPAM range %s; our range is %s", persistedRing.Range(), alloc.universe)
+		return false
+	}
+
+	alloc.ring = persistedRing
+	alloc.space.UpdateRanges(alloc.ring.OwnedRanges())
+
+	if ownedFound {
+		alloc.owned = persistedOwned
+		for _, d := range alloc.owned {
+			for _, cidr := range d.Cidrs {
+				alloc.space.Claim(cidr.Addr)
+			}
+		}
+	}
+	return true
 }
 
 func (alloc *Allocator) persistOwned() {
diff --git a/test/362_ipalloc_range_change.sh b/test/362_ipalloc_range_change.sh
new file mode 100755
index 00000000..d7fab65a
--- /dev/null
+++ b/test/362_ipalloc_range_change.sh
@@ -0,0 +1,14 @@
+#! /bin/bash
+
+. ./config.sh
+
+start_suite "IPAM alloc range change"
+
+weave_on $HOST1 launch --ipalloc-range 10.2.0.0/16
+weave_on $HOST1 prime
+weave_on $HOST1 stop
+weave_on $HOST1 launch --ipalloc-range 10.3.0.0/16
+# Ensure allocations can proceed
+assert_raises "timeout 10 cat <( start_container $HOST1 )"
+
+end_suite
diff --git a/test/380_ipam_seed_2_test.sh b/test/380_ipam_seed_2_test.sh
index 3f18b41b..82184a8e 100755
--- a/test/380_ipam_seed_2_test.sh
+++ b/test/380_ipam_seed_2_test.sh
@@ -19,4 +19,12 @@ weave_on $HOST2 connect $HOST1
 assert_raises "exec_on $HOST1 c1 $PING c2"
 assert_raises "exec_on $HOST2 c2 $PING c1"
 
+# Now restart one router with a different peername
+docker_on $HOST2 rm -f c2 >/dev/null
+weave_on $HOST2 forget $HOST1
+weave_on $HOST2 stop
+weave_on $HOST2 launch --name ::3
+# Check that this host has not retained the previous IPAM data
+assert "weave_on $HOST2 status ipam" ""
+
 end_suite