diff --git a/python/__init__.py b/python/__init__.py
index 6537893a..dd135c4e 100644
--- a/python/__init__.py
+++ b/python/__init__.py
@@ -421,7 +421,7 @@ class Panda:
       except Exception:
         logging.debug("reconnecting is taking %d seconds...", i + 1)
         try:
-          dfu = PandaDFU(PandaDFU.st_serial_to_dfu_serial(self._serial, self._mcu_type))
+          dfu = PandaDFU(self.get_dfu_serial())
           dfu.recover()
         except Exception:
           pass
@@ -493,7 +493,7 @@ class Panda:
       self.reconnect()
 
   def recover(self, timeout: Optional[int] = None, reset: bool = True) -> bool:
-    dfu_serial = PandaDFU.st_serial_to_dfu_serial(self._serial, self._mcu_type)
+    dfu_serial = self.get_dfu_serial()
 
     if reset:
       self.reset(enter_bootstub=True)
@@ -677,6 +677,9 @@ class Panda:
     """
     return self._serial
 
+  def get_dfu_serial(self):
+    return PandaDFU.st_serial_to_dfu_serial(self._serial, self._mcu_type)
+
   def get_uid(self):
     """
       Returns the UID from the MCU
diff --git a/python/spi.py b/python/spi.py
index b742f28f..63be5e44 100644
--- a/python/spi.py
+++ b/python/spi.py
@@ -149,7 +149,7 @@ class PandaSpiHandle(BaseHandle):
         return dat[:-1]
       except PandaSpiException as e:
         exc = e
-        logging.debug("SPI transfer failed, %d retries left", n, exc_info=True)
+        logging.debug("SPI transfer failed, %d retries left", MAX_XFER_RETRY_COUNT - n - 1, exc_info=True)
     raise exc
 
   # libusb1 functions
@@ -201,7 +201,7 @@ class STBootloaderSPIHandle(BaseSTBootloaderHandle):
         spi.xfer([self.SYNC, ])
         try:
           self._get_ack(spi)
-        except PandaSpiNackResponse:
+        except (PandaSpiNackResponse, PandaSpiMissingAck):
           # NACK ok here, will only ACK the first time
           pass
 
@@ -222,7 +222,7 @@ class STBootloaderSPIHandle(BaseSTBootloaderHandle):
     elif data != self.ACK:
       raise PandaSpiMissingAck
 
-  def _cmd(self, cmd: int, data: Optional[List[bytes]] = None, read_bytes: int = 0, predata=None) -> bytes:
+  def _cmd_no_retry(self, cmd: int, data: Optional[List[bytes]] = None, read_bytes: int = 0, predata=None) -> bytes:
     ret = b""
     with self.dev.acquire() as spi:
       # sync + command
@@ -252,6 +252,16 @@ class STBootloaderSPIHandle(BaseSTBootloaderHandle):
 
     return bytes(ret)
 
+  def _cmd(self, cmd: int, data: Optional[List[bytes]] = None, read_bytes: int = 0, predata=None) -> bytes:
+    exc = PandaSpiException()
+    for n in range(MAX_XFER_RETRY_COUNT):
+      try:
+        return self._cmd_no_retry(cmd, data, read_bytes, predata)
+      except PandaSpiException as e:
+        exc = e
+        logging.debug("SPI transfer failed, %d retries left", MAX_XFER_RETRY_COUNT - n - 1, exc_info=True)
+    raise exc
+
   def _checksum(self, data: bytes) -> bytes:
     if len(data) == 1:
       ret = data[0] ^ 0xFF
diff --git a/tests/hitl/0_dfu.py b/tests/hitl/0_dfu.py
index cff4c02c..a8afa24a 100644
--- a/tests/hitl/0_dfu.py
+++ b/tests/hitl/0_dfu.py
@@ -1,8 +1,12 @@
+import pytest
+import random
+
 from panda import Panda, PandaDFU
+from panda.python.spi import SpiDevice
 
 def test_dfu(p):
   app_mcu_type = p.get_mcu_type()
-  dfu_serial = PandaDFU.st_serial_to_dfu_serial(p.get_usb_serial(), p.get_mcu_type())
+  dfu_serial = p.get_dfu_serial()
 
   p.reset(enter_bootstub=True)
   p.reset(enter_bootloader=True)
@@ -16,3 +20,24 @@ def test_dfu(p):
   dfu._handle.clear_status()
   dfu.reset()
   p.reconnect()
+
+
+@pytest.mark.test_panda_types((Panda.HW_TYPE_TRES, ))
+def test_dfu_with_spam(p):
+  dfu_serial = p.get_dfu_serial()
+
+  # enter DFU
+  p.reset(enter_bootstub=True)
+  p.reset(enter_bootloader=True)
+  assert Panda.wait_for_dfu(dfu_serial, timeout=20), "failed to enter DFU"
+
+  # send junk
+  for _ in range(10):
+    speed = 1000000 * random.randint(1, 5)
+    d = SpiDevice(speed=speed)
+    with d.acquire() as spi:
+      dat = [random.randint(0, 255) for _ in range(random.randint(1, 100))]
+      spi.xfer(dat)
+
+  # should still show up
+  assert dfu_serial in PandaDFU.list()
diff --git a/tests/hitl/1_program.py b/tests/hitl/1_program.py
index 6db33550..eb0c6a5a 100644
--- a/tests/hitl/1_program.py
+++ b/tests/hitl/1_program.py
@@ -33,7 +33,7 @@ def test_a_known_bootstub(p):
     p.reset(enter_bootstub=True)
     p.reset(enter_bootloader=True)
 
-    dfu_serial = PandaDFU.st_serial_to_dfu_serial(p._serial, p._mcu_type)
+    dfu_serial = p.get_dfu_serial()
     assert Panda.wait_for_dfu(dfu_serial, timeout=30)
 
     dfu = PandaDFU(dfu_serial)
diff --git a/tests/hitl/conftest.py b/tests/hitl/conftest.py
index 669ae99c..c01538ae 100644
--- a/tests/hitl/conftest.py
+++ b/tests/hitl/conftest.py
@@ -3,7 +3,7 @@ import os
 import time
 import pytest
 
-from panda import Panda
+from panda import Panda, PandaDFU
 from panda_jungle import PandaJungle  # pylint: disable=import-error
 from panda.tests.hitl.helpers import clear_can_buffers
 
@@ -61,6 +61,8 @@ _all_panda_serials = list(_all_pandas.keys())
 
 
 def init_jungle():
+  if _panda_jungle is None:
+    return
   clear_can_buffers(_panda_jungle)
   _panda_jungle.set_panda_power(True)
   _panda_jungle.set_can_loopback(False)
@@ -121,6 +123,11 @@ def func_fixture_panda(request, module_panda):
   yield p
 
   # Teardown
+
+  # reconnect
+  if p.get_dfu_serial() in PandaDFU.list():
+    PandaDFU(p.get_dfu_serial()).reset()
+    p.reconnect()
   if not p.connected:
     p.reconnect()
   if p.bootstub: