diff --git a/ee_plugin/ui/menus.py b/ee_plugin/ui/menus.py
index fde68fb..279b4c4 100644
--- a/ee_plugin/ui/menus.py
+++ b/ee_plugin/ui/menus.py
@@ -1,16 +1,17 @@
 from dataclasses import dataclass, field
-from typing import Optional, List, Union
+from typing import Optional, List, Callable
 from PyQt5.QtWidgets import QMenu, QAction
 
 
-MenuItem = Union["Separator", "SubMenu", "Action"]
+MenuItem = Callable[[QMenu], None]
 
 
-@dataclass
 class Separator:
     """A separator in a menu."""
 
-    ...
+    def __call__(self, menu: QMenu):
+        """Render the separator in the given QMenu."""
+        menu.addSeparator()
 
 
 @dataclass
@@ -20,6 +21,11 @@ class SubMenu:
     label: Optional[str] = None
     subitems: Optional[List[MenuItem]] = field(default_factory=list)
 
+    def __call__(self, menu: QMenu):
+        """Render the submenu in the given QMenu."""
+        sub_menu = menu.addMenu(self.label or "")
+        populate_menu(menu=sub_menu, items=self.subitems)
+
 
 @dataclass
 class Action:
@@ -27,14 +33,12 @@ class Action:
 
     action: Optional[QAction] = None
 
+    def __call__(self, menu: QMenu):
+        """Render the action in the given QMenu."""
+        menu.addAction(self.action)
+
 
 def populate_menu(*, menu: QMenu, items: List[MenuItem]):
     """Populate a QMenu with the given list of MenuItem objects."""
     for item in items:
-        if isinstance(item, Separator):
-            menu.addSeparator()
-        elif isinstance(item, SubMenu):
-            sub_menu = menu.addMenu(item.label or "")
-            populate_menu(menu=sub_menu, items=item.subitems)
-        elif isinstance(item, Action):
-            menu.addAction(item.action)
+        item(menu)