diff --git a/src/wsproto/frame_protocol.py b/src/wsproto/frame_protocol.py
index d13a769..fcb8a13 100644
--- a/src/wsproto/frame_protocol.py
+++ b/src/wsproto/frame_protocol.py
@@ -574,7 +574,7 @@ def close(self, code: Optional[int] = None, reason: Optional[str] = None) -> byt
         if code is None and reason:
             raise TypeError("cannot specify a reason without a code")
         if code in LOCAL_ONLY_CLOSE_REASONS:
-            code = CloseReason.NORMAL_CLOSURE
+            raise ValueError(f"cannot specify a local-only close code, got {code}")
         if code is not None:
             payload += bytearray(struct.pack("!H", code))
             if reason is not None:
diff --git a/test/test_frame_protocol.py b/test/test_frame_protocol.py
index 76c40e4..aef85c5 100644
--- a/test/test_frame_protocol.py
+++ b/test/test_frame_protocol.py
@@ -1043,8 +1043,8 @@ def test_no_status_rcvd_close_reason(self) -> None:
 
     def test_local_only_close_reason(self) -> None:
         proto = fp.FrameProtocol(client=False, extensions=[])
-        data = proto.close(code=fp.CloseReason.ABNORMAL_CLOSURE)
-        assert data == b"\x88\x02\x03\xe8"
+        with pytest.raises(ValueError):
+            proto.close(code=fp.CloseReason.ABNORMAL_CLOSURE)
 
     def test_ping_without_payload(self) -> None:
         proto = fp.FrameProtocol(client=False, extensions=[])