Fix warning

src/connection.h

@@ -49,7 +49,7 @@ req_finalize(struct Client* client, uint8_t cmdset, uint8_t cmdid, size_t length
 
     req->header.preamble = 0x55;
     req->header.length_l = length & 0xFF;
-    req->header.length_h = (length >> 8) & 0x3 | 4;
+    req->header.length_h = ((length >> 8) & 0x3) | 4;
     req->header.crc = crc8(req, 3);
     req->header.seq_id = client->seq++;
     req->header.sender = client->hostbyte;