diff --git a/lib/Serverless.js b/lib/Serverless.js
index 6ce957ab8..197d5e055 100644
--- a/lib/Serverless.js
+++ b/lib/Serverless.js
@@ -49,7 +49,7 @@ class Serverless {
 
   init() {
     // create a new CLI instance
-    this.cli = new CLI(this);
+    this.cli = new this.classes.CLI(this);
 
     // get an array of commands and options that should be processed
     this.processedInput = this.cli.processInput();
diff --git a/lib/Serverless.test.js b/lib/Serverless.test.js
index b33836407..830df7220 100644
--- a/lib/Serverless.test.js
+++ b/lib/Serverless.test.js
@@ -115,6 +115,14 @@ describe('Serverless', () => {
       expect(serverless.cli).to.be.instanceof(CLI);
     });
 
+    it('should allow a custom CLI instance', () => {
+      class CustomCLI extends CLI {}
+      serverless.classes.CLI = CustomCLI;
+      serverless.init();
+      expect(serverless.cli).to.be.instanceof(CLI);
+      expect(serverless.cli.constructor.name).to.equal('CustomCLI');
+    });
+
     // note: we just test that the processedInput variable is set (not the content of it)
     // the test for the correct input is done in the CLI class test file
     it('should receive the processed input form the CLI instance', () => {