diff --git a/builder/virtualbox/step_download_guest_additions.go b/builder/virtualbox/step_download_guest_additions.go
index 2ff2b5d31..2da7d63ed 100644
--- a/builder/virtualbox/step_download_guest_additions.go
+++ b/builder/virtualbox/step_download_guest_additions.go
@@ -2,8 +2,6 @@ package virtualbox
 
 import (
 	"bytes"
-	"crypto/sha256"
-	"encoding/hex"
 	"fmt"
 	"github.com/mitchellh/multistep"
 	"github.com/mitchellh/packer/common"
@@ -34,7 +32,6 @@ type stepDownloadGuestAdditions struct{}
 
 func (s *stepDownloadGuestAdditions) Run(state map[string]interface{}) multistep.StepAction {
 	var action multistep.StepAction
-	cache := state["cache"].(packer.Cache)
 	driver := state["driver"].(Driver)
 	ui := state["ui"].(packer.Ui)
 	config := state["config"].(*config)
@@ -65,12 +62,6 @@ func (s *stepDownloadGuestAdditions) Run(state map[string]interface{}) multistep
 		}
 	}
 
-	checksumBytes, err := hex.DecodeString(checksum)
-	if err != nil {
-		state["error"] = fmt.Errorf("Couldn't decode checksum into bytes: %s", checksum)
-		return multistep.ActionHalt
-	}
-
 	// Use the provided source (URL or file path) or generate it
 	url := config.GuestAdditionsURL
 	if url != "" {
@@ -102,21 +93,15 @@ func (s *stepDownloadGuestAdditions) Run(state map[string]interface{}) multistep
 
 	log.Printf("Guest additions URL: %s", url)
 
-	log.Printf("Acquiring lock to download the guest additions ISO.")
-	cachePath := cache.Lock(url)
-	defer cache.Unlock(url)
-
-	downloadConfig := &common.DownloadConfig{
-		Url:        url,
-		TargetPath: cachePath,
-		Hash:       sha256.New(),
-		Checksum:   checksumBytes,
+	downStep := &common.StepDownload{
+		Checksum:     checksum,
+		ChecksumType: "sha256",
+		Description:  "Guest additions",
+		ResultKey:    "guest_additions_path",
+		Url:          []string{url},
 	}
 
-	download := common.NewDownloadClient(downloadConfig)
-	ui.Say("Downloading VirtualBox guest additions. Progress will be shown periodically.")
-	state["guest_additions_path"], action = s.progressDownload(download, state)
-	return action
+	return downStep.Run(state)
 }
 
 func (s *stepDownloadGuestAdditions) Cleanup(state map[string]interface{}) {}
@@ -165,7 +150,9 @@ DownloadWaitLoop:
 func (s *stepDownloadGuestAdditions) downloadAdditionsSHA256(state map[string]interface{}, additionsVersion string, additionsName string) (string, multistep.StepAction) {
 	// First things first, we get the list of checksums for the files available
 	// for this version.
-	checksumsUrl := fmt.Sprintf("http://download.virtualbox.org/virtualbox/%s/SHA256SUMS", additionsVersion)
+	checksumsUrl := fmt.Sprintf(
+		"http://download.virtualbox.org/virtualbox/%s/SHA256SUMS",
+		additionsVersion)
 
 	checksumsFile, err := ioutil.TempFile("", "packer")
 	if err != nil {
@@ -175,25 +162,23 @@ func (s *stepDownloadGuestAdditions) downloadAdditionsSHA256(state map[string]in
 		return "", multistep.ActionHalt
 	}
 	defer os.Remove(checksumsFile.Name())
-
 	checksumsFile.Close()
 
-	downloadConfig := &common.DownloadConfig{
-		Url:        checksumsUrl,
-		TargetPath: checksumsFile.Name(),
-		Hash:       nil,
+	downStep := &common.StepDownload{
+		Description: "Guest additions checksums",
+		ResultKey:   "guest_additions_checksums_path",
+		TargetPath:  checksumsFile.Name(),
+		Url:         []string{checksumsUrl},
 	}
 
-	log.Printf("Downloading guest addition checksums: %s", checksumsUrl)
-	download := common.NewDownloadClient(downloadConfig)
-	checksumsPath, action := s.progressDownload(download, state)
-	if action != multistep.ActionContinue {
+	action := downStep.Run(state)
+	if action == multistep.ActionHalt {
 		return "", action
 	}
 
 	// Next, we find the checksum for the file we're looking to download.
 	// It is an error if the checksum cannot be found.
-	checksumsF, err := os.Open(checksumsPath)
+	checksumsF, err := os.Open(state["guest_additions_checksums_path"].(string))
 	if err != nil {
 		state["error"] = fmt.Errorf("Error opening guest addition checksums: %s", err)
 		return "", multistep.ActionHalt
@@ -223,7 +208,8 @@ func (s *stepDownloadGuestAdditions) downloadAdditionsSHA256(state map[string]in
 	}
 
 	if checksum == "" {
-		state["error"] = fmt.Errorf("The checksum for the file '%s' could not be found.", additionsName)
+		state["error"] = fmt.Errorf(
+			"The checksum for the file '%s' could not be found.", additionsName)
 		return "", multistep.ActionHalt
 	}
 
diff --git a/common/step_download.go b/common/step_download.go
index 9f97a8eac..f5aff21a6 100644
--- a/common/step_download.go
+++ b/common/step_download.go
@@ -29,6 +29,10 @@ type StepDownload struct {
 	// into the state.
 	ResultKey string
 
+	// The path where the result should go, otherwise it goes to the
+	// cache directory.
+	TargetPath string
+
 	// A list of URLs to attempt to download this thing.
 	Url []string
 }
@@ -37,10 +41,14 @@ func (s *StepDownload) Run(state map[string]interface{}) multistep.StepAction {
 	cache := state["cache"].(packer.Cache)
 	ui := state["ui"].(packer.Ui)
 
-	checksum, err := hex.DecodeString(s.Checksum)
-	if err != nil {
-		state["error"] = fmt.Errorf("Error parsing checksum: %s", err)
-		return multistep.ActionHalt
+	var checksum []byte
+	if s.Checksum != "" {
+		var err error
+		checksum, err = hex.DecodeString(s.Checksum)
+		if err != nil {
+			state["error"] = fmt.Errorf("Error parsing checksum: %s", err)
+			return multistep.ActionHalt
+		}
 	}
 
 	ui.Say(fmt.Sprintf("Downloading or copying %s", s.Description))
@@ -48,13 +56,17 @@ func (s *StepDownload) Run(state map[string]interface{}) multistep.StepAction {
 	var finalPath string
 	for _, url := range s.Url {
 		ui.Message(fmt.Sprintf("Downloading or copying: %s", url))
-		log.Printf("Acquiring lock to download: %s", url)
-		cachePath := cache.Lock(url)
-		defer cache.Unlock(url)
+
+		targetPath := s.TargetPath
+		if targetPath == "" {
+			log.Printf("Acquiring lock to download: %s", url)
+			targetPath = cache.Lock(url)
+			defer cache.Unlock(url)
+		}
 
 		config := &DownloadConfig{
 			Url:        url,
-			TargetPath: cachePath,
+			TargetPath: targetPath,
 			CopyFile:   false,
 			Hash:       HashForType(s.ChecksumType),
 			Checksum:   checksum,