diff --git a/examples/validation/core/17_dev_reload.py b/examples/validation/core/17_dev_reload.py
index bb8de3c1..bb940893 100644
--- a/examples/validation/core/17_dev_reload.py
+++ b/examples/validation/core/17_dev_reload.py
@@ -2,6 +2,7 @@
 from trame.app import get_server, dev
 from trame.widgets import vtk, vuetify
 from trame.ui.vuetify import SinglePageLayout
+from trame_server import Server
 
 # -----------------------------------------------------------------------------
 # Trame setup
@@ -16,14 +17,14 @@ def reset_resolution():
 
 
 # Mode A ----------------------------------------------------------------------
-def full_reload():
+def full_reload(server: Server):
     print("=> Reload mode A")
     dev.remove_change_listeners(server, "resolution")
     dev.reload(sys.modules.get("__main__"))
 
 
 # Mode B ----------------------------------------------------------------------
-def reload_app():
+def reload_app(server: Server):
     print("=> Reload mode B")
     # dev.clear_triggers(app) # Not needed here
     dev.clear_change_listeners(server)
diff --git a/trame/app/dev.py b/trame/app/dev.py
index c1893049..ee391a2d 100644
--- a/trame/app/dev.py
+++ b/trame/app/dev.py
@@ -19,7 +19,7 @@ def clear_change_listeners(server):
     :param server: server on which we want to clear the state.change listeners
     :type server: trame_server.core.Server
     """
-    server._change_callbacks.clear()
+    server.state._change_callbacks.clear()
 
 
 def remove_change_listeners(server, *names):
@@ -34,8 +34,8 @@ def remove_change_listeners(server, *names):
     :type *names: str
     """
     for name in names:
-        if name in server._change_callbacks:
-            server._change_callbacks.pop(name)
+        if name in server.state._change_callbacks:
+            server.state._change_callbacks.pop(name)
 
 
 def reload(*reload_list):