diff --git a/lib/logitech/unifying_receiver/base.py b/lib/logitech/unifying_receiver/base.py
index a9d29b20..2d4b006a 100644
--- a/lib/logitech/unifying_receiver/base.py
+++ b/lib/logitech/unifying_receiver/base.py
@@ -6,9 +6,17 @@
 from __future__ import absolute_import, division, print_function, unicode_literals
 
 from time import time as _timestamp
-from struct import pack as _pack
 from random import getrandbits as _random_bits
 
+from struct import pack as _pack
+try:
+	unicode
+	# if Python2, unicode_literals will mess our first (un)pack() argument
+	_pack_str = _pack
+	_pack = lambda x, *args: _pack_str(str(x), *args)
+except:
+	pass
+
 from logging import getLogger, DEBUG as _DEBUG
 _log = getLogger('LUR.base')
 del getLogger
@@ -145,9 +153,9 @@ def write(handle, devnumber, data):
 	assert isinstance(data, bytes), (repr(data), type(data))
 
 	if len(data) > _SHORT_MESSAGE_SIZE - 2 or data[:1] == b'\x82':
-		wdata = _pack(b'!BB18s', 0x11, devnumber, data)
+		wdata = _pack('!BB18s', 0x11, devnumber, data)
 	else:
-		wdata = _pack(b'!BB5s', 0x10, devnumber, data)
+		wdata = _pack('!BB5s', 0x10, devnumber, data)
 	if _log.isEnabledFor(_DEBUG):
 		_log.debug("(%s) <= w[%02X %02X %s %s]", handle, ord(wdata[:1]), devnumber, _strhex(wdata[2:4]), _strhex(wdata[4:]))
 
@@ -291,10 +299,13 @@ def request(handle, devnumber, request_id, *params):
 	else:
 		timeout = _RECEIVER_REQUEST_TIMEOUT
 
-	params = b''.join(_pack(b'B', p) if isinstance(p, int) else p for p in params)
+	if params:
+		params = b''.join(_pack('B', p) if isinstance(p, int) else p for p in params)
+	else:
+		params = b''
 	# if _log.isEnabledFor(_DEBUG):
 	# 	_log.debug("(%s) device %d request_id {%04X} params [%s]", handle, devnumber, request_id, _strhex(params))
-	request_data = _pack(b'!H', request_id) + params
+	request_data = _pack('!H', request_id) + params
 
 	ihandle = int(handle)
 	notifications_hook = getattr(handle, 'notifications_hook', None)
@@ -378,7 +389,7 @@ def ping(handle, devnumber):
 	# reply, and set most significant (0x8) bit in SoftwareId so that the reply
 	# is always distinguishable from notifications
 	request_id = 0x0018 | _random_bits(3)
-	request_data = _pack(b'!HBBB', request_id, 0, 0, _random_bits(8))
+	request_data = _pack('!HBBB', request_id, 0, 0, _random_bits(8))
 
 	ihandle = int(handle)
 	notifications_hook = getattr(handle, 'notifications_hook', None)
diff --git a/lib/logitech/unifying_receiver/common.py b/lib/logitech/unifying_receiver/common.py
index 443787d9..27c52eaf 100644
--- a/lib/logitech/unifying_receiver/common.py
+++ b/lib/logitech/unifying_receiver/common.py
@@ -6,6 +6,14 @@ from __future__ import absolute_import, division, print_function, unicode_litera
 
 from binascii import hexlify as _hexlify
 from struct import pack as _pack
+try:
+	unicode
+	# if Python2, unicode_literals will mess our first (un)pack() argument
+	_pack_str = _pack
+	_pack = lambda x, *args: _pack_str(str(x), *args)
+except:
+	pass
+
 try:
 	unicode
 	# this is certanly Python 2
@@ -36,7 +44,7 @@ class NamedInt(int):
 	def bytes(self, count=2):
 		if self.bit_length() > count * 8:
 			raise ValueError('cannot fit %X into %d bytes' % (self, count))
-		return _pack(b'!L', self)[-count:]
+		return _pack('!L', self)[-count:]
 
 	def __eq__(self, other):
 		if isinstance(other, NamedInt):
diff --git a/lib/logitech/unifying_receiver/hidpp20.py b/lib/logitech/unifying_receiver/hidpp20.py
index 39d479d9..821fdd76 100644
--- a/lib/logitech/unifying_receiver/hidpp20.py
+++ b/lib/logitech/unifying_receiver/hidpp20.py
@@ -5,6 +5,16 @@
 from __future__ import absolute_import, division, print_function, unicode_literals
 
 from struct import pack as _pack, unpack as _unpack
+try:
+	unicode
+	# if Python2, unicode_literals will mess our first (un)pack() argument
+	_pack_str = _pack
+	_unpack_str = _unpack
+	_pack = lambda x, *args: _pack_str(str(x), *args)
+	_unpack = lambda x, *args: _unpack_str(str(x), *args)
+except:
+	pass
+
 from weakref import proxy as _proxy
 
 from logging import getLogger, DEBUG as _DEBUG
@@ -156,7 +166,7 @@ class FeaturesArray(object):
 				self.device = None
 				return False
 
-			reply = self.device.request(0x0000, _pack(b'!H', FEATURE.FEATURE_SET))
+			reply = self.device.request(0x0000, _pack('!H', FEATURE.FEATURE_SET))
 			if reply is None:
 				self.supported = False
 			else:
@@ -190,7 +200,7 @@ class FeaturesArray(object):
 				if self.features[index] is None:
 					feature = self.device.feature_request(FEATURE.FEATURE_SET, 0x10, index)
 					if feature:
-						feature, = _unpack(b'!H', feature[:2])
+						feature, = _unpack('!H', feature[:2])
 						self.features[index] = FEATURE[feature]
 
 				return self.features[index]
@@ -213,7 +223,7 @@ class FeaturesArray(object):
 					break
 
 			if may_have:
-				reply = self.device.request(0x0000, _pack(b'!H', ivalue))
+				reply = self.device.request(0x0000, _pack('!H', ivalue))
 				if reply:
 					index = ord(reply[0:1])
 					if index:
@@ -233,7 +243,7 @@ class FeaturesArray(object):
 					raise ValueError("%s not in list" % repr(value))
 
 			if may_have:
-				reply = self.device.request(0x0000, _pack(b'!H', ivalue))
+				reply = self.device.request(0x0000, _pack('!H', ivalue))
 				if reply:
 					index = ord(reply[0:1])
 					self.features[index] = FEATURE[ivalue]
@@ -274,7 +284,7 @@ class KeysArray(object):
 			if self.keys[index] is None:
 				keydata = feature_request(self.device, FEATURE.REPROGRAMMABLE_KEYS, 0x10, index)
 				if keydata:
-					key, key_task, flags = _unpack(b'!HHB', keydata[:5])
+					key, key_task, flags = _unpack('!HHB', keydata[:5])
 					self.keys[index] = _ReprogrammableKeyInfo(index, KEY[key], KEY[key_task], flags)
 
 			return self.keys[index]
@@ -327,7 +337,7 @@ def get_firmware(device):
 			if fw_info:
 				level = ord(fw_info[:1]) & 0x0F
 				if level == 0 or level == 1:
-					name, version_major, version_minor, build = _unpack(b'!3sBBH', fw_info[1:8])
+					name, version_major, version_minor, build = _unpack('!3sBBH', fw_info[1:8])
 					version = '%02X.%02X' % (version_major, version_minor)
 					if build:
 						version += '.B%04X' % build
@@ -386,7 +396,7 @@ def get_battery(device):
 	"""
 	battery = feature_request(device, FEATURE.BATTERY)
 	if battery:
-		discharge, dischargeNext, status = _unpack(b'!BBB', battery[:3])
+		discharge, dischargeNext, status = _unpack('!BBB', battery[:3])
 		if _log.isEnabledFor(_DEBUG):
 			_log.debug("device %d battery %d%% charged, next level %d%% charge, status %d = %s",
 						device.number, discharge, dischargeNext, status, BATTERY_STATUS[status])
@@ -402,7 +412,7 @@ def get_keys(device):
 def get_mouse_pointer_info(device):
 	pointer_info = feature_request(device, FEATURE.MOUSE_POINTER)
 	if pointer_info:
-		dpi, flags = _unpack(b'!HB', pointer_info[:3])
+		dpi, flags = _unpack('!HB', pointer_info[:3])
 		acceleration = ['none', 'low', 'med', 'high' ][flags & 0x3]
 		suggest_os_ballistics = (flags & 0x04) != 0
 		suggest_vertical_orientation = (flags & 0x08) != 0
diff --git a/lib/logitech/unifying_receiver/status.py b/lib/logitech/unifying_receiver/status.py
index fe73d105..b9713125 100644
--- a/lib/logitech/unifying_receiver/status.py
+++ b/lib/logitech/unifying_receiver/status.py
@@ -5,9 +5,17 @@
 from __future__ import absolute_import, division, print_function, unicode_literals
 
 from time import time as _timestamp
-from struct import unpack as _unpack
 from weakref import proxy as _proxy
 
+from struct import unpack as _unpack
+try:
+	unicode
+	# if Python2, unicode_literals will mess our first (un)pack() argument
+	_unpack_str = _unpack
+	_unpack = lambda x, *args: _unpack_str(str(x), *args)
+except:
+	pass
+
 from logging import getLogger, DEBUG as _DEBUG
 _log = getLogger('LUR.status')
 del getLogger
@@ -343,7 +351,7 @@ class DeviceStatus(dict):
 
 		if feature == _hidpp20.FEATURE.SOLAR_CHARGE:
 			if n.data[5:9] == b'GOOD':
-				charge, lux, adc = _unpack(b'!BHH', n.data[:5])
+				charge, lux, adc = _unpack('!BHH', n.data[:5])
 				self[BATTERY_LEVEL] = charge
 				# guesstimate the battery voltage, emphasis on 'guess'
 				self[BATTERY_STATUS] = '%1.2fV' % (adc * 2.67793237653 / 0x0672)