diff --git a/plugins/providers/virtualbox/driver/version_4_3.rb b/plugins/providers/virtualbox/driver/version_4_3.rb
index f895739d3..b77b2a4f9 100644
--- a/plugins/providers/virtualbox/driver/version_4_3.rb
+++ b/plugins/providers/virtualbox/driver/version_4_3.rb
@@ -610,6 +610,9 @@ module VagrantPlugins
         def share_folders(folders)
           folders.each do |folder|
             hostpath = folder[:hostpath]
+            if Vagrant::Util::Platform.windows?
+              hostpath = Vagrant::Util::Platform.windows_unc_path(hostpath)
+            end
             args = ["--name",
               folder[:name],
               "--hostpath",