diff --git a/source/dub/dub.d b/source/dub/dub.d
index 5db78ee9b..7d509ca3f 100644
--- a/source/dub/dub.d
+++ b/source/dub/dub.d
@@ -1831,7 +1831,7 @@ private class DependencyVersionResolver : DependencyResolver!(Dependency, Depend
  * nor should it do any file IO, to make it usable and reliable in unittests.
  * Currently it reads environment variables but does not read the configuration.
  */
-package final class TestDub : Dub
+version(unittest) package final class TestDub : Dub
 {
     /// Forward to base constructor
     public this (string root = ".", PackageSupplier[] extras = null,