diff --git a/requirements.txt b/requirements.txt
index 6ab819d..18ad23b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,5 @@
 distro
 pbr>=2.0.0  # Apache-2.0
 Parsley
-packaging
+packaging ; python_version >= '3.6'
+packaging<21.0 ; python_version < '3.6'