diff --git a/packages/jest-runner/src/runTest.js b/packages/jest-runner/src/runTest.js
index 8908a54b58ec..a14bb51dc3ae 100644
--- a/packages/jest-runner/src/runTest.js
+++ b/packages/jest-runner/src/runTest.js
@@ -70,9 +70,10 @@ async function runTestInternal(
     ? require('jest-circus/runner') // eslint-disable-line import/no-extraneous-dependencies
     : /* $FlowFixMe */
       require(config.testRunner)): TestFramework);
-  /* $FlowFixMe */
-  const Runtime = (require(config.moduleLoader ||
-    'jest-runtime'): Class<RuntimeClass>);
+  const Runtime = ((config.moduleLoader
+    ? /* $FlowFixMe */
+      require(config.moduleLoader)
+    : require('jest-runtime')): Class<RuntimeClass>);
 
   let runtime = undefined;
 
diff --git a/packages/jest-runtime/src/index.js b/packages/jest-runtime/src/index.js
index f91e481a2925..25454aef7058 100644
--- a/packages/jest-runtime/src/index.js
+++ b/packages/jest-runtime/src/index.js
@@ -966,4 +966,7 @@ class Runtime {
 }
 
 Runtime.ScriptTransformer = ScriptTransformer;
+
 module.exports = Runtime;
+
+export default Runtime;