diff --git a/lib/ansible/modules/cloud/openstack/os_volume.py b/lib/ansible/modules/cloud/openstack/os_volume.py
index 96d8e57c2c2..87f6dbdb3cb 100644
--- a/lib/ansible/modules/cloud/openstack/os_volume.py
+++ b/lib/ansible/modules/cloud/openstack/os_volume.py
@@ -35,8 +35,9 @@ description:
 options:
    size:
      description:
-        - Size of volume in GB
-     required: only when state is 'present'
+        - Size of volume in GB. This parameter is required when the
+          I(state) parameter is 'present'.
+     required: false
      default: None
    display_name:
      description: