diff --git a/builder/virtualbox/builder.go b/builder/virtualbox/builder.go
index 0e7476eb5..7e2a732de 100644
--- a/builder/virtualbox/builder.go
+++ b/builder/virtualbox/builder.go
@@ -27,6 +27,7 @@ type Builder struct {
 type config struct {
 	BootCommand     []string      `mapstructure:"boot_command"`
 	BootWait        time.Duration ``
+	DiskSize        uint          `mapstructure:"disk_size"`
 	GuestOSType     string        `mapstructure:"guest_os_type"`
 	HTTPDir         string        `mapstructure:"http_directory"`
 	HTTPPortMin     uint          `mapstructure:"http_port_min"`
@@ -61,6 +62,10 @@ func (b *Builder) Prepare(raws ...interface{}) error {
 		}
 	}
 
+	if b.config.DiskSize == 0 {
+		b.config.DiskSize = 40000
+	}
+
 	if b.config.GuestOSType == "" {
 		b.config.GuestOSType = "Other"
 	}
diff --git a/builder/virtualbox/builder_test.go b/builder/virtualbox/builder_test.go
index 6a741d0e1..92b6cae21 100644
--- a/builder/virtualbox/builder_test.go
+++ b/builder/virtualbox/builder_test.go
@@ -75,6 +75,32 @@ func TestBuilderPrepare_BootWait(t *testing.T) {
 	}
 }
 
+func TestBuilderPrepare_DiskSize(t *testing.T) {
+	var b Builder
+	config := testConfig()
+
+	delete(config, "disk_size")
+	err := b.Prepare(config)
+	if err != nil {
+		t.Fatalf("bad err: %s", err)
+	}
+
+	if b.config.DiskSize != 40000 {
+		t.Fatalf("bad size: %d", b.config.DiskSize)
+	}
+
+	config["disk_size"] = 60000
+	b = Builder{}
+	err = b.Prepare(config)
+	if err != nil {
+		t.Fatalf("should not have error: %s", err)
+	}
+
+	if b.config.DiskSize != 60000 {
+		t.Fatalf("bad size: %s", b.config.DiskSize)
+	}
+}
+
 func TestBuilderPrepare_HTTPPort(t *testing.T) {
 	var b Builder
 	config := testConfig()
diff --git a/builder/virtualbox/step_create_disk.go b/builder/virtualbox/step_create_disk.go
index e48825e21..b7d221c2d 100644
--- a/builder/virtualbox/step_create_disk.go
+++ b/builder/virtualbox/step_create_disk.go
@@ -5,6 +5,7 @@ import (
 	"github.com/mitchellh/multistep"
 	"github.com/mitchellh/packer/packer"
 	"path/filepath"
+	"strconv"
 	"strings"
 )
 
@@ -24,7 +25,7 @@ func (s *stepCreateDisk) Run(state map[string]interface{}) multistep.StepAction
 	command := []string{
 		"createhd",
 		"--filename", path,
-		"--size", "40000",
+		"--size", strconv.FormatUint(uint64(config.DiskSize), 10),
 		"--format", format,
 		"--variant", "Standard",
 	}