diff --git a/sway_context_manager/interface.py b/sway_context_manager/interface.py
index 8f71adc..3db5b62 100644
--- a/sway_context_manager/interface.py
+++ b/sway_context_manager/interface.py
@@ -79,15 +79,25 @@ class ContextMngrInterface(
             return ""
         return json.dumps(workspace.__json__())
 
-    def __get_workspace_data(self) -> dict:
+    async def __get_workspace_data(self) -> dict:
         """Get the workspace tree."""
         try:
+            active = self.workspace_tree.current_context.active_workspace
             return {
                 "ws": self.workspace_tree.__json__(),
-                "current": self.workspace_tree.current_context.active_workspace.__json__(),
+                "current": active is not None and active.__json__() or None,
                 "context": self.workspace_tree.current_context.name,
                 "visible": {
-                    name: ws.__json__()
+                    name: ws is not None
+                    and ws.__json__()
+                    or {
+                        "name": f"<undefined:{name}>",
+                        "index": -1,
+                        "active": True,
+                        "visible": True,
+                        "focused": False,
+                        "alerted": False,
+                    }
                     for name, ws in self.workspace_tree.current_context.visible_workspaces.items()
                 },
             }
@@ -98,7 +108,7 @@ class ContextMngrInterface(
     @dbus_method_async(input_signature="", result_signature="s")
     async def get_workspace_data(self) -> str:
         """Get the workspace tree."""
-        data = self.__get_workspace_data()
+        data = await self.__get_workspace_data()
         return json.dumps(data)
 
     @dbus_method_async(input_signature="", result_signature="s")
@@ -114,4 +124,4 @@ class ContextMngrInterface(
 
     async def on_tree_changed(self, workspace_tree: str):
         print("tree changed, emitting signal")
-        self.tree_changed.emit(json.dumps(self.__get_workspace_data()))
+        self.tree_changed.emit(json.dumps(await self.__get_workspace_data()))
diff --git a/sway_context_manager/workspace_tree.py b/sway_context_manager/workspace_tree.py
index ae190ae..49f7a54 100644
--- a/sway_context_manager/workspace_tree.py
+++ b/sway_context_manager/workspace_tree.py
@@ -54,7 +54,14 @@ class Workspace:
         }
 
     def __json__(self):
-        return self.__dict__()
+        return {
+            "index": str(self.index),
+            "name": self.name,
+            "active": self.active,
+            "visible": self.visible,
+            "focused": self.focused,
+            "alerted": self.alerted,
+        }
 
     def __repr__(self):
         return f"Workspace({self.index}, '{self.name}')"