diff --git a/lib/constants.py b/lib/constants.py
index c21a7f4d45457c9e252035269b946cdfe20a9f1c..a483165fb7df1d23ac33528248245bef06b27df1 100644
--- a/lib/constants.py
+++ b/lib/constants.py
@@ -242,6 +242,7 @@ GANETI_RUNAS = "root"
 DEFAULT_VG = "xenvg"
 BIND_ADDRESS_GLOBAL = "0.0.0.0"
 MIN_VG_SIZE = 20480
+DEFAULT_MAC_PREFIX = "aa:00:00"
 
 # RPC constants
 (RPC_ENCODING_NONE,
@@ -401,7 +402,7 @@ ELOG_PROGRESS = "progress"
 RAPI_ENABLE = True
 RAPI_PORT = 5080
 
-# max dynamnic devices
+# max dynamic devices
 MAX_NICS = 8
 MAX_DISKS = 16
 
diff --git a/scripts/gnt-cluster b/scripts/gnt-cluster
index 09c1eb261c20350149f8746183ce5ba2f92cd2fe..862d3642608aec7f2503887e142f404f9129dee0 100755
--- a/scripts/gnt-cluster
+++ b/scripts/gnt-cluster
@@ -541,7 +541,7 @@ commands = {
                         help="Specify the mac prefix for the instance IP"
                         " addresses, in the format XX:XX:XX",
                         metavar="PREFIX",
-                        default="aa:00:00",),
+                        default=constants.DEFAULT_MAC_PREFIX,),
             make_option("-g", "--vg-name", dest="vg_name",
                         help="Specify the volume group name "
                         " (cluster-wide) for disk allocation [xenvg]",