diff --git a/requirements.txt b/requirements.txt
index 5bf176d28..b5be9db56 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -7,3 +7,5 @@ scipy==1.4.1; platform_python_implementation != "PyPy"
 munkres==1.1.2; platform_python_implementation == "PyPy"
 zopfli==0.1.6
 fs==2.4.11
+# this is only required to run Tests/cu2qu/{ufo,cli}_test.py
+ufoLib2==0.6.2