diff --git a/Vagrantfile b/Vagrantfile
index 9e5136b8a5..1171bc0097 100644
--- a/Vagrantfile
+++ b/Vagrantfile
@@ -148,6 +148,12 @@ Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
 
   config.vm.provider "virtualbox" do |vb, override|
     override.vm.box = "ubuntu/trusty64"
+    # An unnecessary log file gets generated when running vagrant up for the
+    # first time with the Ubuntu Bionic box. This looks like it is being
+    # caused upstream by the base box containing a Vagrantfile with a similar
+    # line to the one below.
+    # see https://github.com/hashicorp/vagrant/issues/9425
+    vb.customize [ "modifyvm", :id, "--uartmode1", "disconnected" ]
     # It's possible we can get away with just 1.5GB; more testing needed
     vb.memory = vm_memory
     vb.cpus = vm_num_cpus