diff --git a/setup.py b/setup.py
index 21f2f81..40b6ec0 100644
--- a/setup.py
+++ b/setup.py
@@ -34,6 +34,7 @@
           "attrs >= 16.3.0", # 16.3.0 adds __attrs_post_init__
           "twisted[tls] >= 17.5.0",
           "autobahn[twisted] >= 0.14.1",
+          "setuptools", # pkg_resources
       ],
       extras_require={
           ':sys_platform=="win32"': ["pywin32"],