diff --git a/lib/puppet/parser/functions/is_mac_address.rb b/lib/puppet/parser/functions/is_mac_address.rb
index 1b3088a26..2619d44a3 100644
--- a/lib/puppet/parser/functions/is_mac_address.rb
+++ b/lib/puppet/parser/functions/is_mac_address.rb
@@ -15,7 +15,7 @@ module Puppet::Parser::Functions
 
     mac = arguments[0]
 
-    if /^[a-fA-F0-9]{1,2}:[a-fA-F0-9]{1,2}:[a-fA-F0-9]{1,2}:[a-fA-F0-9]{1,2}:[a-fA-F0-9]{1,2}:[a-fA-F0-9]{1,2}$/.match(mac) then
+    if /^[a-f0-9]{1,2}(:[a-f0-9]{1,2}){5}$/i.match(mac) then
       return true
     else
       return false