diff --git a/plugins/providers/virtualbox/cap/configure_disks.rb b/plugins/providers/virtualbox/cap/configure_disks.rb
index 42e66f6eb..228153120 100644
--- a/plugins/providers/virtualbox/cap/configure_disks.rb
+++ b/plugins/providers/virtualbox/cap/configure_disks.rb
@@ -170,25 +170,22 @@ module VagrantPlugins
 
         def self.vmdk_to_vdi(driver, defined_disk)
           LOGGER.warn("Converting disk '#{defined_disk["Disk Name"]}' from 'vmdk' to 'vdi' format")
-          # todo: MEDIUM changes if virtualbox is older than 5. Need a proper check/switch
-          # Maybe move this into version_4, then version_5
-          # if version 4, medium = "hd"
-          medium = "medium"
-
           source = defined_disk["Location"]
           destination = File.join(File.dirname(source), File.basename(source, ".*")) + ".vdi"
-          driver.execute("clone#{medium}", source, destination, '--format', 'VDI')
+
+          driver.clone_disk(source, destination, 'VDI')
 
           destination
         end
 
         def self.vdi_to_vmdk(driver, defined_disk)
           LOGGER.warn("Converting disk from vdi to vmdk format")
-          medium = "medium"
-
           source = defined_disk["Location"]
           destination = File.join(File.dirname(source), File.basename(source, ".*")) + ".vmdk"
-          driver.execute("clone#{medium}", source, destination, '--format', 'VMDK')
+
+          driver.clone_disk(source, destination, 'VMDK')
+
+          destination
         end
       end
     end
diff --git a/plugins/providers/virtualbox/driver/base.rb b/plugins/providers/virtualbox/driver/base.rb
index f11a78124..1a230018a 100644
--- a/plugins/providers/virtualbox/driver/base.rb
+++ b/plugins/providers/virtualbox/driver/base.rb
@@ -433,7 +433,16 @@ module VagrantPlugins
           execute("createmedium", '--filename', disk_file, '--sizebyte', disk_size.to_i.to_s, '--format', disk_format)
         end
 
-        def clone_disk(disk_file, disk_format="VDI")
+        # @param [String] source
+        # @param [String] destination
+        # @param [String] disk_format
+        def clone_disk(source, destination, disk_format)
+          # todo: MEDIUM changes if virtualbox is older than 5. Need a proper check/switch
+          # Maybe move this into version_4, then version_5
+          # if version 4, medium = "hd"
+          medium = "medium"
+
+          execute("clone#{medium}", source, destination, '--format', disk_format)
         end
 
         # Controller-Port-Device looks like: