diff --git a/install.sh b/install.sh
index 95ad9f6..384aa9d 100644
--- a/install.sh
+++ b/install.sh
@@ -61,6 +61,7 @@ cat <<-EOF > "${TARGET_DIR}${CONFIG_SCRIPT}"
 	/usr/bin/useradd --password ${PASSWORD} --comment 'Vagrant User' --create-home --gid users vagrant
 	echo 'Defaults env_keep += "SSH_AUTH_SOCK"' > /etc/sudoers.d/10_vagrant
 	echo 'vagrant ALL=(ALL) NOPASSWD: ALL' >> /etc/sudoers.d/10_vagrant
+	/usr/bin/chmod 0440 /etc/sudoers.d/10_vagrant
 	/usr/bin/install --directory --owner=vagrant --group=users --mode=0700 /home/vagrant/.ssh
 	/usr/bin/curl --output /home/vagrant/.ssh/authorized_keys https://raw.github.com/mitchellh/vagrant/master/keys/vagrant.pub
 	/usr/bin/chown vagrant:users /home/vagrant/.ssh/authorized_keys