diff --git a/builder/virtualbox/builder_test.go b/builder/virtualbox/builder_test.go
index eb080af47..a2f5b5bb1 100644
--- a/builder/virtualbox/builder_test.go
+++ b/builder/virtualbox/builder_test.go
@@ -119,7 +119,7 @@ func TestBuilderPrepare_GuestAdditionsPath(t *testing.T) {
 	var b Builder
 	config := testConfig()
 
-	delete(config, "disk_size")
+	delete(config, "guest_additions_path")
 	err := b.Prepare(config)
 	if err != nil {
 		t.Fatalf("bad err: %s", err)