diff --git a/types/yeoman-generator/index.d.ts b/types/yeoman-generator/index.d.ts
index 7d461e7b78..7e56c6d497 100644
--- a/types/yeoman-generator/index.d.ts
+++ b/types/yeoman-generator/index.d.ts
@@ -6,6 +6,7 @@
 //                 Joshua Cherry <https://github.com/tasadar2>
 //                 Arthur Corenzan <https://github.com/haggen>
 //                 Richard Lea <https://github.com/chigix>
+//                 Devid Farinelli <https://github.com/misterdev>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.8
 
@@ -87,7 +88,10 @@ declare class Generator extends EventEmitter {
     constructor(args: string|string[], options: {});
 
     env: {
-        error(...e: Error[]): void
+        error(...e: Error[]): void;
+        adapter: {
+            promptModule: inquirer.PromptModule;
+        };
     };
     args: {};
     resolved: string;
@@ -114,6 +118,7 @@ declare class Generator extends EventEmitter {
 
     // actions/help mixin
     argumentsHelp(): string;
+    async(): () => {};
     desc(description: string): this;
     help(): string;
     optionsHelp(): string;
diff --git a/types/yeoman-generator/yeoman-generator-tests.ts b/types/yeoman-generator/yeoman-generator-tests.ts
index c7a6880534..2475c3455e 100644
--- a/types/yeoman-generator/yeoman-generator-tests.ts
+++ b/types/yeoman-generator/yeoman-generator-tests.ts
@@ -1,13 +1,18 @@
 import Base = require('yeoman-generator');
 import { Questions, Answers } from 'yeoman-generator';
 import { EventEmitter } from 'events';
+import * as inquirer from 'inquirer';
 
 class MyES2015Generator extends Base {}
 
 const generator = new MyES2015Generator(['arg1', 'arg2'], { opt1: 'foo', opt2: 3, opt3: false });
 const eventEmitter: EventEmitter = generator;
 
-const env: {} = generator.env;
+const env: {
+  adapter: {
+    promptModule: inquirer.PromptModule;
+  }
+} = generator.env;
 const args: {} = generator.args;
 const resolved: string = generator.resolved;
 const description: string = generator.description;
@@ -41,6 +46,7 @@ generator.argument('arg4', {
 });
 
 const argsHelp = generator.argumentsHelp();
+generator.async();
 
 async function install() {
     generator.installDependencies();