diff --git a/api/ipam.go b/api/ipam.go
index 9f1687dd..d061b420 100644
--- a/api/ipam.go
+++ b/api/ipam.go
@@ -33,8 +33,8 @@ func (client *Client) LookupIP(ID string) (*net.IPNet, error) {
 }
 
 // Claim a specific IP on behalf of the ID
-func (client *Client) ClaimIP(ID string, addr net.IP) error {
-	_, err := client.httpVerb("PUT", fmt.Sprintf("/ip/%s/%s", ID, addr), nil)
+func (client *Client) ClaimIP(ID string, cidr *net.IPNet) error {
+	_, err := client.httpVerb("PUT", fmt.Sprintf("/ip/%s/%s", ID, cidr), nil)
 	return err
 }
 
diff --git a/plugin/ipam/driver.go b/plugin/ipam/driver.go
index 0a965abb..cd37e8d6 100644
--- a/plugin/ipam/driver.go
+++ b/plugin/ipam/driver.go
@@ -73,10 +73,10 @@ func (i *ipam) RequestAddress(poolID string, address net.IP, options map[string]
 		return
 	}
 	if address != nil { // try to claim specific address requested
-		if err = i.weave.ClaimIP("_", address); err != nil {
+		ip = &net.IPNet{IP: address, Mask: subnet.Mask}
+		if err = i.weave.ClaimIP("_", ip); err != nil {
 			return
 		}
-		ip = &net.IPNet{IP: address, Mask: subnet.Mask}
 	} else {
 		if _, iprange, err = net.ParseCIDR(parts[2]); err != nil {
 			return