diff --git a/requirements.in b/requirements.in
index 9ccb349e8831aa907a80a00206a786875d068d7f..55881d393d216e533accde3ea4fc53352bef6c8f 100644
--- a/requirements.in
+++ b/requirements.in
@@ -6,6 +6,7 @@ python-ldap
 # Development and testing.
 ansible-lint
 defusedxml
+flake8
 gimmecert
 molecule[testinfra]~=24.8.0
 molecule-plugins[vagrant]~=23.5.0