diff --git a/python/dfu.py b/python/dfu.py
index b3bf05da1ae1d5..bbab812b0709ea 100644
--- a/python/dfu.py
+++ b/python/dfu.py
@@ -3,6 +3,7 @@
 import usb1
 import struct
 import time
+import binascii
 
 # *** DFU mode ***
 
@@ -46,28 +47,27 @@ def list():
   def st_serial_to_dfu_serial(st):
     if st == None or st == "none":
       return None
-    uid_base = struct.unpack("H"*6, st.decode("hex"))
-    return struct.pack("!HHH", uid_base[1] + uid_base[5], uid_base[0] + uid_base[4] + 0xA, uid_base[3]).encode("hex").upper()
-
+    uid_base = struct.unpack("H"*6, bytes.fromhex(st))
+    return binascii.hexlify(struct.pack("!HHH", uid_base[1] + uid_base[5], uid_base[0] + uid_base[4] + 0xA, uid_base[3])).upper().decode("utf-8")
 
   def status(self):
     while 1:
-      dat = str(self._handle.controlRead(0x21, DFU_GETSTATUS, 0, 0, 6))
-      if dat[1] == "\x00":
+      dat = self._handle.controlRead(0x21, DFU_GETSTATUS, 0, 0, 6)
+      if dat[1] == 0:
         break
 
   def clear_status(self):
     # Clear status
-    stat = str(self._handle.controlRead(0x21, DFU_GETSTATUS, 0, 0, 6))
-    if stat[4] == "\x0a":
+    stat = self._handle.controlRead(0x21, DFU_GETSTATUS, 0, 0, 6)
+    if stat[4] == 0xa:
       self._handle.controlRead(0x21, DFU_CLRSTATUS, 0, 0, 0)
-    elif stat[4] == "\x09":
-      self._handle.controlWrite(0x21, DFU_ABORT, 0, 0, "")
+    elif stat[4] == 0x9:
+      self._handle.controlWrite(0x21, DFU_ABORT, 0, 0, b"")
       self.status()
     stat = str(self._handle.controlRead(0x21, DFU_GETSTATUS, 0, 0, 6))
 
   def erase(self, address):
-    self._handle.controlWrite(0x21, DFU_DNLOAD, 0, 0, "\x41" + struct.pack("I", address))
+    self._handle.controlWrite(0x21, DFU_DNLOAD, 0, 0, b"\x41" + struct.pack("I", address))
     self.status()
 
   def program(self, address, dat, block_size=None):
@@ -75,12 +75,12 @@ def program(self, address, dat, block_size=None):
       block_size = len(dat)
 
     # Set Address Pointer
-    self._handle.controlWrite(0x21, DFU_DNLOAD, 0, 0, "\x21" + struct.pack("I", address))
+    self._handle.controlWrite(0x21, DFU_DNLOAD, 0, 0, b"\x21" + struct.pack("I", address))
     self.status()
 
     # Program
-    dat += "\xFF"*((block_size-len(dat)) % block_size)
-    for i in range(0, len(dat)/block_size):
+    dat += b"\xFF"*((block_size-len(dat)) % block_size)
+    for i in range(0, len(dat)//block_size):
       ldat = dat[i*block_size:(i+1)*block_size]
       print("programming %d with length %d" % (i, len(ldat)))
       self._handle.controlWrite(0x21, DFU_DNLOAD, 2+i, 0, ldat)
@@ -105,17 +105,17 @@ def recover(self):
       build_st(fn)
     fn = os.path.join(BASEDIR, "board", fn)
 
-    with open(fn) as f:
+    with open(fn, "rb") as f:
       code = f.read()
 
     self.program_bootstub(code)
 
   def reset(self):
     # **** Reset ****
-    self._handle.controlWrite(0x21, DFU_DNLOAD, 0, 0, "\x21" + struct.pack("I", 0x8000000))
+    self._handle.controlWrite(0x21, DFU_DNLOAD, 0, 0, b"\x21" + struct.pack("I", 0x8000000))
     self.status()
     try:
-      self._handle.controlWrite(0x21, DFU_DNLOAD, 2, 0, "")
+      self._handle.controlWrite(0x21, DFU_DNLOAD, 2, 0, b"")
       stat = str(self._handle.controlRead(0x21, DFU_GETSTATUS, 0, 0, 6))
     except Exception:
       pass
diff --git a/run_automated_tests.sh b/run_automated_tests.sh
index 583d6c1ed7599a..e876c670a74c0e 100755
--- a/run_automated_tests.sh
+++ b/run_automated_tests.sh
@@ -18,4 +18,4 @@ do
   nmcli connection delete "$NAME"
 done
 
-PYTHONPATH="." python $(which nosetests) -v --with-xunit --xunit-file=./$TEST_FILENAME --xunit-testsuite-name=$TESTSUITE_NAME -s $TEST_SCRIPTS
+PYTHONPATH="." $(which nosetests) -v --with-xunit --xunit-file=./$TEST_FILENAME --xunit-testsuite-name=$TESTSUITE_NAME -s $TEST_SCRIPTS
diff --git a/tests/automated/2_usb_to_can.py b/tests/automated/2_usb_to_can.py
index eba421e531e36d..645f686e155914 100644
--- a/tests/automated/2_usb_to_can.py
+++ b/tests/automated/2_usb_to_can.py
@@ -25,7 +25,7 @@ def test_can_loopback(p):
     p.set_can_speed_kbps(bus, 250)
 
     # send a message on bus 0
-    p.can_send(0x1aa, "message", bus)
+    p.can_send(0x1aa, b"message", bus)
 
     # confirm receive both on loopback and send receipt
     time.sleep(0.05)
@@ -37,7 +37,7 @@ def test_can_loopback(p):
 
     # confirm data is correct
     assert 0x1aa == sr[0][0] == lb[0][0]
-    assert "message" == sr[0][2] == lb[0][2]
+    assert b"message" == sr[0][2] == lb[0][2]
 
 @test_all_pandas
 @panda_connect_and_init
@@ -49,7 +49,7 @@ def test_safety_nooutput(p):
   p.set_can_loopback(True)
 
   # send a message on bus 0
-  p.can_send(0x1aa, "message", 0)
+  p.can_send(0x1aa, b"message", 0)
 
   # confirm receive nothing
   time.sleep(0.05)
@@ -68,7 +68,7 @@ def test_reliability(p):
   p.set_can_speed_kbps(0, 1000)
 
   addrs = list(range(100, 100+MSG_COUNT))
-  ts = [(j, 0, "\xaa"*8, 0) for j in addrs]
+  ts = [(j, 0, b"\xaa"*8, 0) for j in addrs]
 
   # 100 loops
   for i in range(LOOP_COUNT):
@@ -182,4 +182,4 @@ def test_gmlan_bad_toggle(p):
 def test_serial_debug(p):
   junk = p.serial_read(Panda.SERIAL_DEBUG)
   p.call_control_api(0xc0)
-  assert(p.serial_read(Panda.SERIAL_DEBUG).startswith("can "))
+  assert(p.serial_read(Panda.SERIAL_DEBUG).startswith(b"can "))
diff --git a/tests/automated/6_two_panda.py b/tests/automated/6_two_panda.py
index d15f98ee7f81a6..711b83fddf63e6 100644
--- a/tests/automated/6_two_panda.py
+++ b/tests/automated/6_two_panda.py
@@ -18,7 +18,7 @@ def test_send_recv(p_send, p_recv):
   assert not p_send.legacy
   assert not p_recv.legacy
 
-  p_send.can_send_many([(0x1ba, 0, "message", 0)]*2)
+  p_send.can_send_many([(0x1ba, 0, b"message", 0)]*2)
   time.sleep(0.05)
   p_recv.can_recv()
   p_send.can_recv()
@@ -55,7 +55,7 @@ def test_latency(p_send, p_recv):
   p_recv.set_can_speed_kbps(0, 100)
   time.sleep(0.05)
 
-  p_send.can_send_many([(0x1ba, 0, "testmsg", 0)]*10)
+  p_send.can_send_many([(0x1ba, 0, b"testmsg", 0)]*10)
   time.sleep(0.05)
   p_recv.can_recv()
   p_send.can_recv()
@@ -80,7 +80,7 @@ def test_latency(p_send, p_recv):
 
       for i in range(num_messages):
         st = time.time()
-        p_send.can_send(0x1ab, "message", bus)
+        p_send.can_send(0x1ab, b"message", bus)
         r = []
         while len(r) < 1 and (time.time() - st) < 5:
           r = p_recv.can_recv()
@@ -127,7 +127,7 @@ def test_black_loopback(panda0, panda1):
   panda1.set_can_loopback(False)
 
   # clear stuff
-  panda0.can_send_many([(0x1ba, 0, "testmsg", 0)]*10)
+  panda0.can_send_many([(0x1ba, 0, b"testmsg", 0)]*10)
   time.sleep(0.05)
   panda0.can_recv()
   panda1.can_recv()
@@ -155,7 +155,7 @@ def get_test_string():
   def _test_buses(send_panda, recv_panda, _test_array):
     for send_bus, send_obd, recv_obd, recv_buses in _test_array:
       print("\nSend bus:", send_bus, " Send OBD:", send_obd, " Recv OBD:", recv_obd)
-      
+
       # set OBD on pandas
       send_panda.set_gmlan(True if send_obd else None)
       recv_panda.set_gmlan(True if recv_obd else None)
@@ -180,7 +180,7 @@ def _test_buses(send_panda, recv_panda, _test_array):
         loop_buses.append(loop[3])
       if len(cans_loop) == 0:
         print("  No loop")
-      
+
       # test loop buses
       recv_buses.sort()
       loop_buses.sort()
@@ -192,4 +192,4 @@ def _test_buses(send_panda, recv_panda, _test_array):
   print("***************** TESTING (0 --> 1) *****************")
   _test_buses(panda0, panda1, test_array)
   print("***************** TESTING (1 --> 0) *****************")
-  _test_buses(panda1, panda0, test_array)
\ No newline at end of file
+  _test_buses(panda1, panda0, test_array)
diff --git a/tests/automated/helpers.py b/tests/automated/helpers.py
index 370e696d8393bc..6c469598f3d180 100644
--- a/tests/automated/helpers.py
+++ b/tests/automated/helpers.py
@@ -140,7 +140,7 @@ def time_many_sends(p, bus, precv=None, msg_count=100, msg_id=None, two_pandas=F
     raise ValueError("Cannot have two pandas that are the same panda")
 
   st = time.time()
-  p.can_send_many([(msg_id, 0, "\xaa"*8, bus)]*msg_count)
+  p.can_send_many([(msg_id, 0, b"\xaa"*8, bus)]*msg_count)
   r = []
   r_echo = []
   r_len_expected = msg_count if two_pandas else msg_count*2