diff --git a/changelogs/fragments/su_fix.yml b/changelogs/fragments/su_fix.yml
new file mode 100644
index 00000000000..f03ba0343da
--- /dev/null
+++ b/changelogs/fragments/su_fix.yml
@@ -0,0 +1,2 @@
+bugfixes:
+  - su become plugin, ensure correct type for localization option.
diff --git a/lib/ansible/plugins/become/su.py b/lib/ansible/plugins/become/su.py
index 3d6a07b5b00..77e997648ab 100644
--- a/lib/ansible/plugins/become/su.py
+++ b/lib/ansible/plugins/become/su.py
@@ -72,6 +72,7 @@ DOCUMENTATION = """
                 - List of localized strings to match for prompt detection
                 - If empty we'll use the built in one
             default: []
+            type: list
             ini:
               - section: su_become_plugin
                 key: localized_prompts