diff --git a/blueman/bluez/AgentManager.py b/blueman/bluez/AgentManager.py
index 9f266e1b5..1fe249f1b 100644
--- a/blueman/bluez/AgentManager.py
+++ b/blueman/bluez/AgentManager.py
@@ -13,7 +13,7 @@ def __init__(self) -> None:
 
     def register_agent(self, agent_path: str, capability: str = "", default: bool = False) -> None:
         param = GLib.Variant('(os)', (agent_path, capability))
-        self._call('RegisterAgent', param)
+        self._call_sync('RegisterAgent', param)
         if default:
             default_param = GLib.Variant('(o)', (agent_path,))
             self._call('RequestDefaultAgent', default_param)
diff --git a/blueman/bluez/Base.py b/blueman/bluez/Base.py
index af6458899..ab4ec9f65 100644
--- a/blueman/bluez/Base.py
+++ b/blueman/bluez/Base.py
@@ -94,6 +94,9 @@ def callback(
 
         self.__proxy.call(method, param, Gio.DBusCallFlags.NONE, GLib.MAXINT, None,
                           callback, reply_handler, error_handler)
+        
+    def _call_sync(self, method: str, param: GLib.Variant | None = None) -> GLib.Variant | None:
+        return self.__proxy.call_sync(method, param, Gio.DBusCallFlags.NONE, -1, None)
 
     def get(self, name: str) -> Any:
         try: