diff --git a/plugins/vagrant/_vagrant b/plugins/vagrant/_vagrant
index d55ae6709..aa18da474 100644
--- a/plugins/vagrant/_vagrant
+++ b/plugins/vagrant/_vagrant
@@ -49,7 +49,7 @@ __box_list ()
 
 __vm_list ()
 {
-    _wanted application expl 'command' compadd $(command grep Vagrantfile -oe '^[^#]*\.vm\.define *:\([a-zA-Z0-9]\+\)' 2>/dev/null | cut -d: -f2)
+    _wanted application expl 'command' compadd $(command grep Vagrantfile -oe '^[^#]*\.vm\.define *:\([-_a-zA-Z0-9]\+\)' 2>/dev/null | cut -d: -f2)
 }
 
 __vagrant-box ()