diff --git a/assets/babel-plugin.js b/assets/babel-plugin.js
index 3b1632534c..e11162bf8e 100644
--- a/assets/babel-plugin.js
+++ b/assets/babel-plugin.js
@@ -1,22 +1,27 @@
 const path = require('path');
-
 // A lame copy-paste from src/index.ts
 function getWebDependencyName(dep) {
   return dep.replace(/\.js$/, '');
 }
 
-function rewriteBareModuleImport(imp, addMissingJsExtensions) {
-  const extname = addMissingJsExtensions && '.js';
-  if (imp.startsWith('/') || imp.startsWith('.')|| imp.startsWith('\\')) {
-    if (extname && !path.extname(imp)) imp += extname;
-    return imp;
+function rewriteImport(imp, shouldAddMissingExtension) {
+  const isSourceImport = imp.startsWith('/') || imp.startsWith('.')|| imp.startsWith('\\');
+  if (!isSourceImport) {
+    return `/web_modules/${getWebDependencyName(imp)}.js`;
+  }
+  if (shouldAddMissingExtension && !path.extname(imp)) {
+    return imp + '.js';
   }
-  return `/web_modules/${getWebDependencyName(imp)}.js`;
+  return imp;
 }
 
-module.exports = function pikaWebBabelTransform({types: t}, options) {
-  const addMissingJsExtensions = options.addMissingJsExtensions;
-  const rewriteBareModuleName = options.rewriteBareModuleName || rewriteBareModuleImport;
+/**
+ * BABEL OPTIONS:
+ *   extensionsOptional - Adds any missing JS extensions to local/relative imports. Support for these
+ *                        partial imports is missing in the browser and being phased out of Node.js, but
+ *                        this can be a useful option for migrating an old project to @pika/web.
+ */
+module.exports = function pikaWebBabelTransform({types: t}, {extensionsOptional}) {
   return {
     visitor: {
       CallExpression(path, {file, opts}) {
@@ -32,7 +37,7 @@ module.exports = function pikaWebBabelTransform({types: t}, options) {
 
 
         source.replaceWith(
-          t.stringLiteral(rewriteBareModuleName(source.node.value, addMissingJsExtensions)),
+          t.stringLiteral(rewriteImport(source.node.value, extensionsOptional)),
         );
       },
       'ImportDeclaration|ExportNamedDeclaration|ExportAllDeclaration'(path, {file, opts}) {
@@ -44,7 +49,7 @@ module.exports = function pikaWebBabelTransform({types: t}, options) {
         }
 
         source.replaceWith(
-          t.stringLiteral(rewriteBareModuleName(source.node.value, addMissingJsExtensions)),
+          t.stringLiteral(rewriteImport(source.node.value, extensionsOptional)),
         );
       },
     },