diff --git a/gns3server/compute/qemu/qemu_vm.py b/gns3server/compute/qemu/qemu_vm.py
index 95d414fe..894cad8c 100644
--- a/gns3server/compute/qemu/qemu_vm.py
+++ b/gns3server/compute/qemu/qemu_vm.py
@@ -533,7 +533,7 @@ class QemuVM(BaseNode):
 
         if not mac_address:
             # use the node UUID to generate a random MAC address
-            self._mac_address = "0C:%s:%s:%s:%s:00" % (self.project.id[-4:-2], self.project.id[-2:], self.id[-4:-2], self.id[-2:])
+            self._mac_address = "0c:%s:%s:%s:%s:00" % (self.project.id[-4:-2], self.project.id[-2:], self.id[-4:-2], self.id[-2:])
         else:
             self._mac_address = mac_address