diff --git a/spec/unit/driver/cli_spec.rb b/spec/unit/driver/cli_spec.rb
index 5ff5b0f..54e848b 100644
--- a/spec/unit/driver/cli_spec.rb
+++ b/spec/unit/driver/cli_spec.rb
@@ -146,9 +146,17 @@ describe Vagrant::LXC::Driver::CLI do
     end
 
     it 'supports a "namespaces" parameter' do
+      subject.stub(:run).with(:attach, '-h').and_return('--namespaces')
       subject.attach *(command + [{namespaces: ['network', 'mount']}])
       subject.should have_received(:run).with(:attach, '--name', name, '--namespaces', 'NETWORK|MOUNT', '--', *command)
     end
+
+    it 'raises a NamespacesNotSupported error if not supported' do
+      subject.stub(:run).with(:attach, '-h').and_return('not supported')
+      expect {
+        subject.attach *(command + [{namespaces: ['network', 'mount']}])
+      }.to raise_error(Vagrant::LXC::Errors::NamespacesNotSupported)
+    end
   end
 
   describe 'transition block' do