diff --git a/frontend/ui/data/onetime_migration.lua b/frontend/ui/data/onetime_migration.lua
index 84fc9a144..8dc23bdf4 100644
--- a/frontend/ui/data/onetime_migration.lua
+++ b/frontend/ui/data/onetime_migration.lua
@@ -12,7 +12,7 @@ local util = require("util")
 local _ = require("gettext")
 
 -- Date at which the last migration snippet was added
-local CURRENT_MIGRATION_DATE = 20250601
+local CURRENT_MIGRATION_DATE = 20250629
 
 -- Retrieve the date of the previous migration, if any
 local last_migration_date = G_reader_settings:readSetting("last_migration_date", 0)
@@ -888,6 +888,28 @@ if last_migration_date < 20250601 then
     SettingsMigration:migrateSettings(G_reader_settings)
 end
 
+-- 20250629, Fix trailing slashes in wallabag directories #13987
+-- https://github.com/koreader/koreader/issues/13987
+if last_migration_date < 20250629 then
+    logger.info("Performing one-time migration for 20250629")
+
+    local wb_lua = DataStorage:getSettingsDir() .. "/wallabag.lua"
+    if lfs.attributes(wb_lua, "mode") == "file" then
+        local wb_settings = LuaSettings:open(wb_lua)
+        wb_settings:readSetting("wallabag")
+
+        if wb_settings.data.wallabag.directory:sub(-1) ~= "/" then
+            wb_settings.data.wallabag.directory = wb_settings.data.wallabag.directory .. "/"
+        end
+
+        if wb_settings.data.wallabag.archive_directory:sub(-1) ~= "/" then
+            wb_settings.data.wallabag.archive_directory = wb_settings.data.wallabag.archive_directory .. "/"
+        end
+
+        wb_settings:saveSetting("wallabag", wb_settings.data.wallabag)
+        wb_settings:flush()
+    end
+end
 
 -- We're done, store the current migration date
 G_reader_settings:saveSetting("last_migration_date", CURRENT_MIGRATION_DATE)
diff --git a/plugins/wallabag.koplugin/main.lua b/plugins/wallabag.koplugin/main.lua
index 8f7c4947d..1fce18a02 100644
--- a/plugins/wallabag.koplugin/main.lua
+++ b/plugins/wallabag.koplugin/main.lua
@@ -566,11 +566,6 @@ function Wallabag:getBearerToken()
         return false
     end
 
-    -- Add trailing slash if it is missing
-    if string.sub(self.directory, -1) ~= "/" then
-        self.directory = self.directory .. "/"
-    end
-
     -- Check if token is valid for at least 5 minutes. If so, no need to renew
     local now = os.time()
     if self.token_expiry - now > 300 then
@@ -1528,9 +1523,9 @@ end
 function Wallabag:setDownloadDirectory(touchmenu_instance)
     require("ui/downloadmgr"):new{
         onConfirm = function(path)
-            self.directory = path
+            self.directory = path .. "/"
             self:saveSettings()
-            logger.dbg("Wallabag:setDownloadDirectory: set download directory to", path)
+            logger.dbg("Wallabag:setDownloadDirectory: set download directory to", self.directory)
             if touchmenu_instance then
                 touchmenu_instance:updateItems()
             end
@@ -1542,9 +1537,9 @@ end
 function Wallabag:setArchiveDirectory(touchmenu_instance)
     require("ui/downloadmgr"):new{
         onConfirm = function(path)
-            self.archive_directory = path
+            self.archive_directory = path .. "/"
             self:saveSettings()
-            logger.dbg("Wallabag:setArchiveDirectory: set archive directory to", path)
+            logger.dbg("Wallabag:setArchiveDirectory: set archive directory to", self.archive_directory)
             if touchmenu_instance then
                 touchmenu_instance:updateItems()
             end