diff --git a/python/uds.py b/python/uds.py
index 416c344696cbae..18e29aca9d9bfe 100644
--- a/python/uds.py
+++ b/python/uds.py
@@ -151,9 +151,9 @@ def _isotp_thread(panda, bus, tx_addr, tx_queue, rx_queue):
           assert tx_frame["done"] == False, "tx: no active frame"
           # TODO: support wait/overflow
           assert rx_data[0] == 0x30, "tx: flow-control requires: continue"
-          delay_ts = ord(rx_data[2]) & 0x7F
+          delay_ts = rx_data[2] & 0x7F
           # scale is 1 milliseconds if first bit == 0, 100 micro seconds if first bit == 1
-          delay_div = 1000. if ord(rx_data[2]) & 0x80 == 0 else 10000.
+          delay_div = 1000. if rx_data[2] & 0x80 == 0 else 100000.
           # first frame = 6 bytes, each consecutive frame = 7 bytes
           start = 6 + tx_frame["idx"] * 7
           count = rx_data[1]
@@ -164,7 +164,7 @@ def _isotp_thread(panda, bus, tx_addr, tx_queue, rx_queue):
             msg = (chr(0x20 | (tx_frame["idx"] & 0xF)) + tx_frame["data"][i:i+7]).ljust(8, "\x00")
             if (DEBUG): print("S: {} {}".format(hex(tx_addr), hexlify(msg)))
             panda.can_send(tx_addr, msg, bus)
-            if delay_ts:
+            if delay_ts > 0:
               time.sleep(delay_ts / delay_div)
           tx_frame["done"] = True