diff --git a/src/index.ts b/src/index.ts
index 1f8bc46ab0..338a527f4c 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,6 +1,7 @@
 import { defaultRetrieveFileHandler } from './default-retrieve-file-handler';
 import * as sourceMapSupport from 'source-map-support';
 
+export { transpileIfTypescript } from './transpile-if-ts';
 export function install() {
   var options: sourceMapSupport.Options = {};
   options.retrieveFile = defaultRetrieveFileHandler;
diff --git a/src/transpile-if-ts.ts b/src/transpile-if-ts.ts
index 2c9c596ef0..f7cbd2afc7 100644
--- a/src/transpile-if-ts.ts
+++ b/src/transpile-if-ts.ts
@@ -1,11 +1,11 @@
 import * as tsc from 'typescript';
 import { getTSConfig } from './utils';
 
-export function transpileIfTypescript(path, contents) {
+export function transpileIfTypescript(path, contents, config?) {
   if (path && (path.endsWith('.tsx') || path.endsWith('.ts'))) {
 
     let transpiled = tsc.transpileModule(contents, {
-      compilerOptions: getTSConfig({ __TS_CONFIG__: global['__TS_CONFIG__'] }, true),
+      compilerOptions: getTSConfig(config || { __TS_CONFIG__: global['__TS_CONFIG__'] }, true),
       fileName: path
     });
 
diff --git a/tests/__tests__/transpileIfTypescript.spec.ts b/tests/__tests__/transpileIfTypescript.spec.ts
new file mode 100644
index 0000000000..5a6d04b0fb
--- /dev/null
+++ b/tests/__tests__/transpileIfTypescript.spec.ts
@@ -0,0 +1,19 @@
+import { transpileIfTypescript } from '../../src';
+
+describe.only('transpileIfTypescript', () => {
+    it('should ignore anything non-TS', () => {
+        const contents = 'unaltered';
+        expect(transpileIfTypescript('some.js', contents)).toBe(contents);
+    });
+    it('should be able to transpile some TS', () => {
+        const ts = 'const x:string = "anything";';
+        expect(transpileIfTypescript('some.ts', ts)).toMatch('var x = "anything";');
+        expect(transpileIfTypescript('some.tsx', ts)).toMatch('var x = "anything";');
+    });
+
+    it('should be possible to pass a custom config', () => {
+        const customTsConfigFile = 'not-existant.json';
+        const customConfig = { __TS_CONFIG__: customTsConfigFile};
+        expect(() => transpileIfTypescript('some.ts', '', customConfig)).toThrow(new RegExp(customTsConfigFile));
+    });
+});
\ No newline at end of file