diff --git a/lib/vagrant-libvirt/cap/nic_mac_addresses.rb b/lib/vagrant-libvirt/cap/nic_mac_addresses.rb
index f8f4c5c..c6164ae 100644
--- a/lib/vagrant-libvirt/cap/nic_mac_addresses.rb
+++ b/lib/vagrant-libvirt/cap/nic_mac_addresses.rb
@@ -3,7 +3,13 @@ module VagrantPlugins
     module Cap
       class NicMacAddresses
         def self.nic_mac_addresses(machine)
-          machine.provider.mac_addresses
+          # Vagrant expects a Hash with an index starting at 1 as key
+          # and the mac as uppercase string without colons as value
+          nic_macs = {}
+          machine.provider.mac_addresses.each do |index, mac|
+            nic_macs[index+1] = mac.upcase.gsub(':','')
+          end
+          nic_macs
         end
       end
     end