diff --git a/setup.py b/setup.py
index ac7b8cab41a66810f376c607c662e4977d8872d4..811b84ff8bb2a8d7c3637968a2c42a585d7b2e6e 100644
--- a/setup.py
+++ b/setup.py
@@ -30,7 +30,7 @@ setup(
     setup_requires=[
         'pytest-runner>=2.6.2',
     ],
-    tests_require=[check-manifest>=0.25',
+    tests_require=['check-manifest>=0.25',
                    'isort>=4.2.2',
                    'pydocstyle>=1.0.0',
                    'pytest-asyncio>=0.8.0',