diff --git a/lib/virtualbox/vm.rb b/lib/virtualbox/vm.rb
index f13fe73..ae4f5d6 100644
--- a/lib/virtualbox/vm.rb
+++ b/lib/virtualbox/vm.rb
@@ -472,7 +472,7 @@ def start(mode="gui")
       # as well
       session = Lib.lib.session
       interface.launch_vm_process(session, mode.to_s, "").wait
-      session.unlock_machine
+      session.unlock_machine if session.state == :open
       true
     end