diff --git a/requirements.txt b/requirements.txt
index a94bee987..fe9030c30 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1,2 @@
 brotli==0.5.2
+unicodedata2==9.0.0.post4; python_version < '3.6' and platform_python_implementation != "PyPy"