diff --git a/test/fixtures/transformation/optional-external-runtime/basic/actual.js b/test/fixtures/transformation/optional-external-runtime/basic/actual.js
new file mode 100644
index 0000000000..9e9515cece
--- /dev/null
+++ b/test/fixtures/transformation/optional-external-runtime/basic/actual.js
@@ -0,0 +1 @@
+import * as foo from "someModule";
diff --git a/test/fixtures/transformation/optional-external-runtime/basic/expected.js b/test/fixtures/transformation/optional-external-runtime/basic/expected.js
new file mode 100644
index 0000000000..b10bbe6f09
--- /dev/null
+++ b/test/fixtures/transformation/optional-external-runtime/basic/expected.js
@@ -0,0 +1,5 @@
+"use strict";
+
+var _to5Runtime = require("6to5-runtime");
+
+var foo = _to5Runtime.interopRequireWildcard(require("someModule"));
diff --git a/test/fixtures/transformation/optional-external-runtime/options.json b/test/fixtures/transformation/optional-external-runtime/options.json
new file mode 100644
index 0000000000..44c5164a67
--- /dev/null
+++ b/test/fixtures/transformation/optional-external-runtime/options.json
@@ -0,0 +1,4 @@
+{
+  "runtime": "6to5-runtime",
+  "optional": ["externalRuntime"]
+}