diff --git a/README.md b/README.md
index c52c09c..eaabafb 100644
--- a/README.md
+++ b/README.md
@@ -47,15 +47,15 @@ describe('Some tests', () => {
   });
 
   // Run the bin and do something with the result
-  test('a test', () => {
+  test('a test', async () => {
     const result = await runBin();
 
     expect(result.stdout).toBe('Did some stuff');
   });
 
-  test('another test', () => {
+  test('another test', async () => {
     // Write a file with contents to the tmp directory
-    await project.writeJSON({
+    await project.writeDirJSON({
       'some/file.txt': 'some content',
     });
 
@@ -93,7 +93,7 @@ describe('Some tests', () => {
     * [new BinTesterProject(name, version, cb)](#new_BinTesterProject_new)
     * [.gitInit()](#BinTesterProject+gitInit) ⇒ <code>\*</code>
     * [.chdir()](#BinTesterProject+chdir)
-    * [.writeJSON(dirJSON)](#BinTesterProject+writeJSON) ⇒ <code>\*</code>
+    * [.writeDirJSON(dirJSON)](#BinTesterProject+writeDirJSON) ⇒ <code>\*</code>
     * [.dispose()](#BinTesterProject+dispose) ⇒ <code>void</code>
 
 <a name="new_BinTesterProject_new"></a>
@@ -121,9 +121,9 @@ describe('Some tests', () => {
 <p>Changes a directory from inside the project.</p>
 
 **Kind**: instance method of [<code>BinTesterProject</code>](#BinTesterProject)  
-<a name="BinTesterProject+writeJSON"></a>
+<a name="BinTesterProject+writeDirJSON"></a>
 
-### binTesterProject.writeJSON(dirJSON) ⇒ <code>\*</code>
+### binTesterProject.writeDirJSON(dirJSON) ⇒ <code>\*</code>
 <p>Writes a directory struture in the project directory.</p>
 
 **Kind**: instance method of [<code>BinTesterProject</code>](#BinTesterProject)  
diff --git a/src/create-bin-tester.ts b/src/create-bin-tester.ts
index 4048090..460390b 100644
--- a/src/create-bin-tester.ts
+++ b/src/create-bin-tester.ts
@@ -12,7 +12,7 @@ interface BinTesterOptions<TProject> {
   /**
    * An optional function to use to create the project. Use this if you want to provide a custom implementation of a BinTesterProject.
    */
-  createProject?: () => TProject;
+  createProject?: () => Promise<TProject>;
 }
 
 interface RunOptions {
diff --git a/src/project.ts b/src/project.ts
index dbb3863..1502256 100644
--- a/src/project.ts
+++ b/src/project.ts
@@ -51,7 +51,7 @@ export default class BinTesterProject extends Project {
    * @param {fixturify.DirJSON} dirJSON - A JSON object representing the directory structure to create.
    * @returns {*} {Promise<void>}
    */
-  writeJSON(dirJSON: fixturify.DirJSON): Promise<void> {
+  writeDirJSON(dirJSON: fixturify.DirJSON): Promise<void> {
     this.files = deepmerge(this.files, dirJSON);
 
     return this.write();