diff --git a/usr/local/share/bastille/common.sh b/usr/local/share/bastille/common.sh
index 316e8718..38181b5e 100644
--- a/usr/local/share/bastille/common.sh
+++ b/usr/local/share/bastille/common.sh
@@ -73,8 +73,9 @@ warn() {
 generate_static_mac() {
     local jail_name="${1}"
     local external_interface="${2}"
-    local macaddr_prefix="$(ifconfig ${external_interface} | grep ether | awk '{print $2}' | cut -d':' -f1-3)"
-    local macaddr_suffix="$(echo -n "${external_interface}${jail_name}" | sha256 | cut -b -5 | sed 's/\([0-9a-fA-F][0-9a-fA-F]\)\([0-9a-fA-F][0-9a-fA-F]\)\([0-9a-fA-F]\)/\1:\2:\3/')"
+    local external_interface_mac="$(ifconfig ${external_interface} | grep ether | awk '{print $2}' | sed 's#:##g')"
+    local macaddr_prefix="$(echo -n "${external_interface_mac}" | sha256 | cut -b -6 | sed 's/\([0-9a-fA-F][0-9a-fA-F]\)\([0-9a-fA-F][0-9a-fA-F]\)\([0-9a-fA-F]\)/\1:\2:\3/')"
+    local macaddr_suffix="$(echo -n "${jail_name}" | sha256 | cut -b -5 | sed 's/\([0-9a-fA-F][0-9a-fA-F]\)\([0-9a-fA-F][0-9a-fA-F]\)\([0-9a-fA-F]\)/\1:\2:\3/')"
     if [ -z "${macaddr_prefix}" ] || [ -z "${macaddr_suffix}" ]; then
         error_notify "Failed to generate MAC address."
     fi