diff --git a/mitmproxy/connection.py b/mitmproxy/connection.py
index 41e5e7ddd..d38e23caf 100644
--- a/mitmproxy/connection.py
+++ b/mitmproxy/connection.py
@@ -291,8 +291,12 @@ class Server(Connection):
         return f"Server({human.format_address(self.address)}, state={self.state.name.lower()}{tls_state}{local_port})"
 
     def __setattr__(self, name, value):
-        if name == "address" and self.__dict__.get("state", ConnectionState.CLOSED) is ConnectionState.OPEN:
-            raise RuntimeError("Cannot change server address on open connection.")
+        if name == "address":
+            connection_open = self.__dict__.get("state", ConnectionState.CLOSED) is ConnectionState.OPEN
+            # assigning the current value is okay, that may be an artifact of calling .set_state().
+            address_changed = self.__dict__.get("address") != value
+            if connection_open and address_changed:
+                raise RuntimeError("Cannot change server address on open connection.")
         return super().__setattr__(name, value)
 
     def get_state(self):
diff --git a/test/mitmproxy/test_connection.py b/test/mitmproxy/test_connection.py
index bf685a361..5f3f23dc0 100644
--- a/test/mitmproxy/test_connection.py
+++ b/test/mitmproxy/test_connection.py
@@ -85,3 +85,5 @@ class TestServer:
         s.state = ConnectionState.OPEN
         with pytest.raises(RuntimeError):
             s.address = ("example.com", 80)
+        # No-op assignment, allowed because it might be triggered by a Server.set_state() call.
+        s.address = ("example.com", 443)