diff --git a/src/middleware/slugify/uniqueSlug.spec.js b/src/middleware/slugify/uniqueSlug.spec.js
index 3d379bafb..190899795 100644
--- a/src/middleware/slugify/uniqueSlug.spec.js
+++ b/src/middleware/slugify/uniqueSlug.spec.js
@@ -3,16 +3,16 @@ import uniqueSlug from './uniqueSlug'
 describe('uniqueSlug', () => {
   it('slugifies given string', () => {
     const string = 'Hello World'
-    const isUnique = () => true
-    expect(uniqueSlug(string, isUnique)).toEqual('hello-world')
+    const isUnique = jest.fn()
+      .mockResolvedValue(true)
+    expect(uniqueSlug(string, isUnique)).resolves.toEqual('hello-world')
   })
 
   it('increments slugified string until unique', () => {
     const string = 'Hello World'
     const isUnique = jest.fn()
-    isUnique
-      .mockReturnValueOnce(false)
-      .mockReturnValueOnce(true)
-    expect(uniqueSlug(string, isUnique)).toEqual('hello-world-1')
+      .mockResolvedValueOnce(false)
+      .mockResolvedValueOnce(true)
+    expect(uniqueSlug(string, isUnique)).resolves.toEqual('hello-world-1')
   })
 })