diff --git a/requirements-dev.txt b/requirements-dev.txt
index 17613a38..c44b676a 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -6,3 +6,6 @@ flake8
 mock
 pylint<1.4
 pytest
+
+# setuptools breaks pypy3 with extraneous output
+setuptools<18.5