diff --git a/weaver/weave b/weaver/weave
index de0e72e7..2870314e 100755
--- a/weaver/weave
+++ b/weaver/weave
@@ -131,25 +131,21 @@ container_netns_cleanup() {
 # Parameters are container ID, CIDR address
 configure_container_networking() {
     container_netns_preamble $1
+    EXITCODE=1
+    IP_TMPFILE=/tmp/weave_ip_output_$$
+    rm -f $IP_TMPFILE
 
     # If veth name already exists then assume we set it up already;
     # just add the IP address, if it's not already there
     if ip link show $LOCAL_IFNAME >/dev/null 2>&1 ; then
-        if ! ip netns exec $NSPID ip addr list dev $CONTAINER_IFNAME | grep -qF $2 ; then
-            if ! ip netns exec $NSPID ip addr add $2 dev $CONTAINER_IFNAME ; then
-                echo "Failed to attach address $2 to container $1" >&2
-                container_netns_cleanup
-                return 1
+        if ! (ip netns exec $NSPID ip addr list dev $CONTAINER_IFNAME | grep -qF $2) 2>$IP_TMPFILE ; then
+            if ip netns exec $NSPID ip addr add $2 dev $CONTAINER_IFNAME 2>$IP_TMPFILE ; then
+                EXITCODE=0  # succeeded in adding the address
             fi
+        else
+            EXITCODE=0      # address was there already
         fi
-        container_netns_cleanup
-        return 0
-    fi
-
-    EXITCODE=1
-    IP_TMPFILE=/tmp/weave_ip_output_$$
-    rm -f $IP_TMPFILE
-    if ip link add name $LOCAL_IFNAME mtu $MTU type veth peer name $GUEST_IFNAME mtu $MTU >$IP_TMPFILE 2>&1 ; then
+    elif ip link add name $LOCAL_IFNAME mtu $MTU type veth peer name $GUEST_IFNAME mtu $MTU >$IP_TMPFILE 2>&1 ; then
         if  (ip link set $LOCAL_IFNAME master $BRIDGE &&
                 ip link set $LOCAL_IFNAME up &&
                 ip link set $GUEST_IFNAME netns $NSPID) >$IP_TMPFILE 2>&1
@@ -185,23 +181,33 @@ detach() {
     container_netns_preamble $1
 
     EXITCODE=1
-    if ip netns exec $NSPID ip addr list dev $CONTAINER_IFNAME | grep -qF $2 ; then
-        if ip netns exec $NSPID ip addr del $2 dev $CONTAINER_IFNAME ; then
+    IP_TMPFILE=/tmp/weave_ip_output_$$
+    rm -f $IP_TMPFILE
+    if (ip netns exec $NSPID ip addr list dev $CONTAINER_IFNAME | grep -qF $2) 2>$IP_TMPFILE ; then
+        if ip netns exec $NSPID ip addr del $2 dev $CONTAINER_IFNAME 2>$IP_TMPFILE ; then
             # if no inet addresses remain then delete the veth
-            if [ -z "$(ip netns exec $NSPID ip -f inet addr list dev ethwe)" ] ; then
-                if ip link del $LOCAL_IFNAME type veth ; then
+            if [ -z "$(ip netns exec $NSPID ip -f inet addr list dev ethwe 2>$IP_TMPFILE)" ] ; then
+                if ip link del $LOCAL_IFNAME type veth 2>$IP_TMPFILE ; then
                     EXITCODE=0
-                else
-                    echo "Failed to delete virtual ethernet device $LOCAL_IFNAME from container $1" >&2
                 fi
             else
                 EXITCODE=0
             fi
+        fi
+    else
+        EXITCODE=0
+    fi
+
+    if [ "$EXITCODE" -ne 0 ] ; then
+        if ! ps -p $DOCKERPID >/dev/null 2>&1 ; then
+            echo "Container $1 died" >&2
         else
-            echo "Failed to detach address $2 from container $1" >&2
+            echo "Failure while detaching address $2 from container $1" >&2
+            cat $IP_TMPFILE >&2
         fi
     fi
 
+    rm -f $IP_TMPFILE
     container_netns_cleanup
     return $EXITCODE
 }