diff --git a/mdb/models.py b/mdb/models.py
index f2e9d97..b74f017 100644
--- a/mdb/models.py
+++ b/mdb/models.py
@@ -2,7 +2,7 @@ from django.db import models
 from django.db.models.signals import post_save, pre_save, pre_delete
 from django.dispatch import receiver
 
-from validators import validate_hostname
+from validators import validate_hostname, validate_macaddr
 
 import ipaddr
 import datetime
@@ -556,7 +556,7 @@ class Host(models.Model):
 
 class Interface(models.Model):
     name = models.CharField(max_length=128)
-    macaddr = models.CharField(max_length=17)
+    macaddr = models.CharField(max_length=17, validators=[validate_macaddr])
     pxe_filename = models.CharField(max_length=64, blank=True)
     dhcp_client = models.BooleanField(default=False)
     host = models.ForeignKey(Host)
diff --git a/mdb/validators.py b/mdb/validators.py
index 91861a5..58bfb1b 100644
--- a/mdb/validators.py
+++ b/mdb/validators.py
@@ -1,5 +1,15 @@
 from django.core.validators import RegexValidator
 import re
+
 # http://en.wikipedia.org/wiki/Hostname#Restrictions_on_valid_host_names
 hostname_re = re.compile(r'^(?!-)[-a-z0-9]+(?<!-)$', re.IGNORECASE)
-validate_hostname = RegexValidator(hostname_re, u'Enter a valid hostname', 'invalid')
+validate_hostname = RegexValidator(
+    regex=hostname_re,
+    message=u'Enter a valid hostname',
+    code='invalid')
+
+macaddr_re = re.compile(r'^([0-9A-F]{2}[:]){5}([0-9A-F]{2})$', re.IGNORECASE)
+validate_macaddr = RegexValidator(
+    regex=macaddr_re,
+    message=u'Enter a valid MAC address',
+    code='invalid')