diff --git a/io/channel-websock.c b/io/channel-websock.c
index bb545fa327..03c1f7cb62 100644
--- a/io/channel-websock.c
+++ b/io/channel-websock.c
@@ -746,7 +746,7 @@ static int qio_channel_websock_decode_header(QIOChannelWebsock *ioc,
             opcode != QIO_CHANNEL_WEBSOCK_OPCODE_CLOSE &&
             opcode != QIO_CHANNEL_WEBSOCK_OPCODE_PING &&
             opcode != QIO_CHANNEL_WEBSOCK_OPCODE_PONG) {
-            error_setg(errp, "unsupported opcode: %#04x; only binary, close, "
+            error_setg(errp, "unsupported opcode: 0x%04x; only binary, close, "
                        "ping, and pong websocket frames are supported", opcode);
             qio_channel_websock_write_close(
                 ioc, QIO_CHANNEL_WEBSOCK_STATUS_INVALID_DATA ,