diff --git a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-from-ra.sh b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-from-ra.sh
index 9a5586b..18341fe 100644
--- a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-from-ra.sh
+++ b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-from-ra.sh
@@ -27,7 +27,7 @@
   local pfx
   for pfx in "${!gbmc_br_from_ra_pfxs[@]}"; do
     local cidr
-    if ! cidr="$(ipv6_pfx_to_cidr "$pfx")"; then
+    if ! cidr="$(ip_pfx_to_cidr "$pfx")"; then
       unset 'gbmc_br_from_ra_pfxs[$pfx]'
       continue
     fi
@@ -38,8 +38,12 @@
         continue
       fi
       local addr
-      addr="$(ipv6_pfx_concat "$pfx" "$sfx")"
+      if ! addr="$(ip_pfx_concat "$pfx" "$sfx")"; then
+        unset 'gbmc_br_from_ra_pfxs[$pfx]'
+        continue
+      fi
     else
+      unset 'gbmc_br_from_ra_pfxs[$pfx]'
       continue
     fi
     local valid="${gbmc_br_from_ra_pfxs["$pfx"]}"
diff --git a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-nft.sh b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-nft.sh
index 185d78b..19b8f64 100644
--- a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-nft.sh
+++ b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-nft.sh
@@ -56,10 +56,14 @@
       echo "gBMC Bridge NFT Invalid IP: $ip" >&2
       return 1
     fi
-    if (( ip_bytes[9] != 0xfd )); then
+    if (( ip_bytes[8] != 0xfd )); then
       return 0
     fi
-    pfx="$(printf '%02x%02x:%02x%02x:%02x%02x:%02x%02x:fd00::/72' "${ip_bytes[@]}")"
+    local i
+    for (( i=9; i<16; i++ )); do
+      ip_bytes[$i]=0
+    done
+    pfx="$(ip_bytes_to_str ip_bytes)/72"
     if [ "$action" = "add" -a "$pfx" != "$gbmc_br_nft_pfx" ]; then
       gbmc_br_nft_pfx="$pfx"
       gbmc_br_nft_update
diff --git a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-ula.sh b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-ula.sh
index ac273a3..6989710 100644
--- a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-ula.sh
+++ b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-ula.sh
@@ -27,10 +27,11 @@
   local addr=
   contents='[Network]'$'\n'
   if [ -n "$gbmc_br_ula_mac" ]; then
-    local eui64
-    eui64="$(mac_to_eui64 "$mac")" || return
-    addr="fdb5:0481:10ce:0:$eui64/64"
-    contents+="Address=$addr"$'\n'
+    local sfx
+    if sfx="$(mac_to_eui64 "$gbmc_br_ula_mac")" &&
+       addr="$(ip_pfx_concat "fdb5:0481:10ce::/64" "$sfx")"; then
+      contents+="Address=$addr"$'\n'
+    fi
   fi
 
   local netfile