diff --git a/src/Options.ts b/src/Options.ts
index 18d3c757..0e9d0c1c 100644
--- a/src/Options.ts
+++ b/src/Options.ts
@@ -46,12 +46,21 @@ export default class Options {
     readonly stdio: boolean,
     readonly help: boolean,
     readonly dry: boolean
-  ) {}
+  ) {
+    const defaultFileSystemExtensions = new Set(['.js']);
+    if (transpilePluginsWithTypescript) {
+      {
+        defaultFileSystemExtensions.add('.ts');
+      }
+    }
 
-  private pluginLoader = new PluginLoader([
-    new FileSystemResolver(),
-    new PackageResolver()
-  ]);
+    this.pluginLoader = new PluginLoader([
+      new FileSystemResolver(defaultFileSystemExtensions),
+      new PackageResolver()
+    ]);
+  }
+
+  private pluginLoader: PluginLoader;
 
   private remotePluginLoader = new PluginLoader([
     new AstExplorerResolver(),
@@ -110,16 +119,15 @@ export default class Options {
     }
   }
 
-  
   loadTypescriptTranspile() {
-    try{
+    try {
       require.resolve('typescript');
     } catch (e) {
-      throw new Error('Typescript is not installed locally. You must installed Typescript locally in order to transpile plugins written in Typescript');
+      throw new Error(
+        'Typescript is not installed locally. You must installed Typescript locally in order to transpile plugins written in Typescript'
+      );
     }
 
-    //TODO: what about options????
-
     require('ts-node').register();
   }
 
diff --git a/test/cli/CLITest.ts b/test/cli/CLITest.ts
index e6e43d09..8397be95 100644
--- a/test/cli/CLITest.ts
+++ b/test/cli/CLITest.ts
@@ -254,6 +254,30 @@ describe('CLI', function() {
     strictEqual(await readFile(afile, 'utf8'), '4 + 5;');
   });
 
+  it('can load plugins written in Typescript without ts extension', async function() {
+    let afile = await createTemporaryFile('a-file.js', '3 + 4;');
+    let pluginFile = join(
+      __dirname,
+      '../fixtures/plugin/typescript/increment-typescript'
+    );
+    let { status, stdout, stderr } = await runCodemodCLI([
+      afile,
+      '-p',
+      pluginFile,
+      '--transpile-ts-plugins'
+    ]);
+
+    deepEqual(
+      { status, stdout, stderr },
+      {
+        status: 0,
+        stdout: `${afile}\n1 file(s), 1 modified, 0 errors\n`,
+        stderr: ''
+      }
+    );
+    strictEqual(await readFile(afile, 'utf8'), '4 + 5;');
+  });
+
   it('can load plugins with multiple files written in Typescript', async function() {
     let afile = await createTemporaryFile('a-file.js', '3 + 4;');
     let pluginFile = join(
@@ -277,4 +301,28 @@ describe('CLI', function() {
     );
     strictEqual(await readFile(afile, 'utf8'), '4 + 5;');
   });
+
+  it('can load plugins with multiple files written in Typescript and Javascript', async function() {
+    let afile = await createTemporaryFile('a-file.js', '3 + 4;');
+    let pluginFile = join(
+      __dirname,
+      '../fixtures/plugin/typescript/increment-export-default-multiple/increment-export-index.ts'
+    );
+    let { status, stdout, stderr } = await runCodemodCLI([
+      afile,
+      '-p',
+      pluginFile,
+      '--transpile-ts-plugins'
+    ]);
+
+    deepEqual(
+      { status, stdout, stderr },
+      {
+        status: 0,
+        stdout: `${afile}\n1 file(s), 1 modified, 0 errors\n`,
+        stderr: ''
+      }
+    );
+    strictEqual(await readFile(afile, 'utf8'), '4 + 5;');
+  });
 });
diff --git a/test/fixtures/plugin/typescript/increment-export-default-multiple/increment-export-default-js.js b/test/fixtures/plugin/typescript/increment-export-default-multiple/increment-export-default-js.js
new file mode 100644
index 00000000..3a04ca07
--- /dev/null
+++ b/test/fixtures/plugin/typescript/increment-export-default-multiple/increment-export-default-js.js
@@ -0,0 +1,3 @@
+export function incrementValue(x) {
+  return x + 1;
+}
diff --git a/test/fixtures/plugin/typescript/increment-export-default-multiple/increment-export-index.ts b/test/fixtures/plugin/typescript/increment-export-default-multiple/increment-export-index.ts
new file mode 100644
index 00000000..1a85e16d
--- /dev/null
+++ b/test/fixtures/plugin/typescript/increment-export-default-multiple/increment-export-index.ts
@@ -0,0 +1,13 @@
+import { incrementValue } from './increment-export-default-js';
+
+/* tslint:disable */
+export default function() {
+  return {
+    visitor: {
+      NumericLiteral(path) {
+        let value: number = path.node.value;
+        path.node.value = incrementValue(value);
+      }
+    }
+  };
+}