diff --git a/matrix_client/room.py b/matrix_client/room.py
index 2964ead2..830649c9 100644
--- a/matrix_client/room.py
+++ b/matrix_client/room.py
@@ -411,7 +411,7 @@ def set_room_name(self, name):
         except MatrixRequestError:
             return False
 
-    def send_state_event(self, event_type, content, state_key):
+    def send_state_event(self, event_type, content, state_key=""):
         """Send a state event to the room.
 
         Args: