diff --git a/tests/utils/shippable/units.sh b/tests/utils/shippable/units.sh
index dc58415db9..b24b08432a 100755
--- a/tests/utils/shippable/units.sh
+++ b/tests/utils/shippable/units.sh
@@ -22,6 +22,11 @@ esac
 
 ansible-test env --timeout "${timeout}" --color -v
 
+if [ "$2" == "2.9" ]; then
+    # 1.5.0+ will not install for Python 3.6+ in the 2.9 setting (due to `enum` being installed)
+    echo "pynacl >= 1.4.0, < 1.5.0; python_version >= '3.6'" >> tests/unit/requirements.txt
+fi
+
 if [ "$2" == "2.10" ]; then
     sed -i -E 's/^redis($| .*)/redis < 4.1.0/g' tests/unit/requirements.txt
     sed -i -E 's/^python-gitlab($| .*)/python-gitlab < 2.10.1 ; python_version >= '\'3.6\''/g' tests/unit/requirements.txt