diff --git a/README.md b/README.md
index a7f5c499..3a241d72 100644
--- a/README.md
+++ b/README.md
@@ -69,7 +69,7 @@ ansible-galaxy install datadog.datadog
 | `datadog_agent_allow_downgrade`                                                                                                                 | Set to `yes` to allow Agent downgrades on apt-based platforms (use with caution, see `defaults/main.yml` for details). **On centos this will only work with ansible 2.4 and up**.                                                                        |
 | `use_apt_backup_keyserver`                                                                                                                      | Set `true` to use the backup keyserver instead of the default one.                                                                                                                                                                                       |
 | `datadog_enabled`                                                                                                                               | Set to `false` to prevent `datadog-agent` service from starting. Defaults to `true`                                                                                                                                                                      |
-| `datadog_additional_groups`                                                                                                                     | Comma separated list of additional groups for the `datadog_user`. Linux only.                                                                                                                                                                            |
+| `datadog_additional_groups`                                                                                                                     | Either a list, or a string containing a comma-separated list of additional groups for the `datadog_user`. Linux only.                                                                                                                                                                            |
 | `datadog_windows_ddagentuser_name`                                                                                                              | Name of windows user to create/use, in the format `<domain>\<user>`.  Windows only.                                                                                                                                                                      |
 | `datadog_windows_ddagentuser_password`                                                                                                          | Password to use to create the user, and/or register the service. Windows only.                                                                                                                                                                           |
 
diff --git a/tasks/agent-linux.yml b/tasks/agent-linux.yml
index dca9d6be..738acb32 100644
--- a/tasks/agent-linux.yml
+++ b/tasks/agent-linux.yml
@@ -4,7 +4,6 @@
 
 - name: add "{{ datadog_user }}" user to additional groups
   user: name="{{ datadog_user }}" groups="{{ datadog_additional_groups }}" append=yes
-  with_items: "{{ datadog_additional_groups }}"
   when: datadog_additional_groups is defined and (datadog_additional_groups | length != 0)
   notify: restart datadog-agent