--- a/pvl/dhcp/config.py	Mon Mar 02 00:15:17 2015 +0200
+++ b/pvl/dhcp/config.py	Mon Mar 02 00:19:39 2015 +0200
@@ -3,8 +3,7 @@
 import string
 
 # simplified model of lexer chars
-TOKEN_START = string.ascii_letters
-TOKEN = TOKEN_START + string.digits + '-_.'
+TOKEN = string.ascii_letters + string.digits + '-_.:'
 
 class DHCPConfigError(Exception):
     def __init__ (self, parser, error, line=None):
@@ -76,9 +75,7 @@
 
     if isinstance(value, int):
         return str(value)
-    elif not value:
-        return ''
-    elif value[0] in TOKEN_START and all(c in TOKEN for c in value):
+    elif all(c in TOKEN for c in value):
         return str(value)
     else:
         # quoted

--- a/pvl/dhcp/tests.py	Mon Mar 02 00:15:17 2015 +0200
+++ b/pvl/dhcp/tests.py	Mon Mar 02 00:19:39 2015 +0200
@@ -85,10 +85,20 @@
     filename "/debian/wheezy/pxelinux.0";
 
     include "hosts/test.conf";
+
+    host test {
+        fixed-address       192.0.2.1;
+        hardware ethernet   00:11:22:33:44:55;
+    }
 }
         """)), (('group', ), [
             ('next-server', 'boot.test'),
             ('filename', "/debian/wheezy/pxelinux.0"),
             ('include', "hosts/test.conf"),
-        ], []))
+        ], [
+            (('host', 'test'), [
+                ('fixed-address', '192.0.2.1'),
+                ('hardware', 'ethernet', '00:11:22:33:44:55'),
+            ], [])
+        ]))