diff --git a/modules/webapp/src/main/elm/App/Data.elm b/modules/webapp/src/main/elm/App/Data.elm
index 4c3a4c6c..845a9555 100644
--- a/modules/webapp/src/main/elm/App/Data.elm
+++ b/modules/webapp/src/main/elm/App/Data.elm
@@ -14,6 +14,7 @@ import Data.Flags exposing (Flags)
 import Data.UiSettings exposing (UiSettings)
 import Data.UiTheme exposing (UiTheme)
 import Http
+import Messages.UiLanguage exposing (UiLanguage)
 import Page exposing (Page(..))
 import Page.CollectiveSettings.Data
 import Page.Home.Data
@@ -25,7 +26,6 @@ import Page.Queue.Data
 import Page.Register.Data
 import Page.Upload.Data
 import Page.UserSettings.Data
-import UiLanguage exposing (UiLanguage)
 import Url exposing (Url)
 
 
@@ -101,7 +101,7 @@ init key url flags_ settings =
       , uiSettings = settings
       , sidebarVisible = settings.sideMenuVisible
       , anonymousTheme = Data.UiTheme.Light
-      , anonymousUiLang = UiLanguage.English
+      , anonymousUiLang = Messages.UiLanguage.English
       , langMenuOpen = False
       }
     , Cmd.batch
@@ -163,7 +163,7 @@ type Msg
 
 
 defaultPage : Flags -> Page
-defaultPage flags =
+defaultPage _ =
     HomePage
 
 
diff --git a/modules/webapp/src/main/elm/App/View2.elm b/modules/webapp/src/main/elm/App/View2.elm
index 0cf078cf..c8afa599 100644
--- a/modules/webapp/src/main/elm/App/View2.elm
+++ b/modules/webapp/src/main/elm/App/View2.elm
@@ -9,6 +9,7 @@ import Html.Attributes exposing (..)
 import Html.Events exposing (onClick)
 import Messages exposing (Messages)
 import Messages.App exposing (Texts)
+import Messages.UiLanguage
 import Page exposing (Page(..))
 import Page.CollectiveSettings.View2 as CollectiveSettings
 import Page.Home.Data
@@ -22,7 +23,6 @@ import Page.Register.View2 as Register
 import Page.Upload.View2 as Upload
 import Page.UserSettings.View2 as UserSettings
 import Styles as S
-import UiLanguage
 
 
 view : Model -> List (Html Msg)
@@ -198,7 +198,7 @@ langMenu model =
             [ class dropdownMenu
             , classList [ ( "hidden", not model.langMenuOpen ) ]
             ]
-            (List.map langItem UiLanguage.all)
+            (List.map langItem Messages.UiLanguage.all)
         ]
 
 
diff --git a/modules/webapp/src/main/elm/Comp/UiSettingsForm.elm b/modules/webapp/src/main/elm/Comp/UiSettingsForm.elm
index d7f8c6a0..4162917c 100644
--- a/modules/webapp/src/main/elm/Comp/UiSettingsForm.elm
+++ b/modules/webapp/src/main/elm/Comp/UiSettingsForm.elm
@@ -30,9 +30,9 @@ import Http
 import Markdown
 import Messages
 import Messages.Comp.UiSettingsForm exposing (Texts)
+import Messages.UiLanguage exposing (UiLanguage)
 import Set exposing (Set)
 import Styles as S
-import UiLanguage exposing (UiLanguage)
 import Util.Maybe
 import Util.Tag
 
@@ -150,7 +150,7 @@ init flags settings =
       , powerSearchEnabled = settings.powerSearchEnabled
       , uiLang = settings.uiLang
       , uiLangModel =
-            Comp.FixedDropdown.init UiLanguage.all
+            Comp.FixedDropdown.init Messages.UiLanguage.all
       , openTabs = Set.empty
       }
     , Api.getTags flags "" GetTagsResp
diff --git a/modules/webapp/src/main/elm/Data/UiSettings.elm b/modules/webapp/src/main/elm/Data/UiSettings.elm
index 1a69438b..8e1e3cd0 100644
--- a/modules/webapp/src/main/elm/Data/UiSettings.elm
+++ b/modules/webapp/src/main/elm/Data/UiSettings.elm
@@ -31,7 +31,7 @@ import Dict exposing (Dict)
 import Html exposing (Attribute)
 import Html.Attributes as HA
 import Messages
-import UiLanguage exposing (UiLanguage)
+import Messages.UiLanguage exposing (UiLanguage)
 
 
 {-| Settings for the web ui. All fields should be optional, since it
@@ -167,7 +167,7 @@ defaults =
     , uiTheme = Data.UiTheme.Light
     , sideMenuVisible = True
     , powerSearchEnabled = False
-    , uiLang = UiLanguage.English
+    , uiLang = Messages.UiLanguage.English
     }
 
 
@@ -222,7 +222,7 @@ merge given fallback =
     , powerSearchEnabled = given.powerSearchEnabled
     , uiLang =
         Maybe.map Messages.fromIso2 given.uiLang
-            |> Maybe.withDefault UiLanguage.English
+            |> Maybe.withDefault Messages.UiLanguage.English
     }
 
 
diff --git a/modules/webapp/src/main/elm/Messages.elm b/modules/webapp/src/main/elm/Messages.elm
index d69c99ba..06857527 100644
--- a/modules/webapp/src/main/elm/Messages.elm
+++ b/modules/webapp/src/main/elm/Messages.elm
@@ -16,7 +16,7 @@ import Messages.Page.Queue
 import Messages.Page.Register
 import Messages.Page.Upload
 import Messages.Page.UserSettings
-import UiLanguage exposing (UiLanguage(..))
+import Messages.UiLanguage exposing (UiLanguage(..))
 
 
 {-| The messages record contains all strings used in the application.
@@ -66,7 +66,7 @@ readIso2 iso =
         isIso lang =
             iso == toIso2 lang
     in
-    List.filter isIso UiLanguage.all
+    List.filter isIso Messages.UiLanguage.all
         |> List.head
 
 
@@ -81,6 +81,8 @@ fromIso2 iso =
 
 
 --- Messages Definitions
+-- for flag icons, see https://github.com/lipis/flag-icon-css
+-- use two classes: flag-icon flag-icon-xx where xx is the two-letter country code
 
 
 gb : Messages
diff --git a/modules/webapp/src/main/elm/UiLanguage.elm b/modules/webapp/src/main/elm/Messages/UiLanguage.elm
similarity index 58%
rename from modules/webapp/src/main/elm/UiLanguage.elm
rename to modules/webapp/src/main/elm/Messages/UiLanguage.elm
index 05a46f61..57446cec 100644
--- a/modules/webapp/src/main/elm/UiLanguage.elm
+++ b/modules/webapp/src/main/elm/Messages/UiLanguage.elm
@@ -1,8 +1,11 @@
-module UiLanguage exposing
+module Messages.UiLanguage exposing
     ( UiLanguage(..)
     , all
     )
 
+{-| This module defines the languages supported in the web app.
+-}
+
 
 type UiLanguage
     = English