diff --git a/packages/dev-utils/src/chai_setup.ts b/packages/dev-utils/src/chai_setup.ts
index 71d8649dfd..a3c3f98410 100644
--- a/packages/dev-utils/src/chai_setup.ts
+++ b/packages/dev-utils/src/chai_setup.ts
@@ -1,3 +1,4 @@
+import { RevertError } from '@0x/utils';
 import * as chai from 'chai';
 import chaiAsPromised = require('chai-as-promised');
 import ChaiBigNumber = require('chai-bignumber');
@@ -5,6 +6,14 @@ import * as dirtyChai from 'dirty-chai';
 
 import { revertErrorHelper } from './chai_revert_error';
 
+declare global {
+    namespace Chai {
+        export interface Assertion {
+            revertWith: (expected: string | RevertError) => Promise<void>;
+        }
+    }
+}
+
 export const chaiSetup = {
     configure(): void {
         chai.config.includeStack = true;
diff --git a/packages/typescript-typings/types/@0x/index.d.ts b/packages/typescript-typings/types/@0x/index.d.ts
deleted file mode 100644
index 123fe211f9..0000000000
--- a/packages/typescript-typings/types/@0x/index.d.ts
+++ /dev/null
@@ -1,6 +0,0 @@
-// tslint:disable: no-namespace
-declare namespace Chai {
-    interface Assertion {
-        revertWith: (expected: string | RevertError) => Promise<void>;
-    }
-}