diff --git a/pySim/cards.py b/pySim/cards.py
index b4b5fdf..053ea98 100644
--- a/pySim/cards.py
+++ b/pySim/cards.py
@@ -89,7 +89,7 @@
 		"""
 		# get size and write EF.OPLMNwAcT
 		data = self._scc.read_binary(EF['OPLMNwAcT'], length=None, offset=0)
-		size = len(data[0])/2
+		size = len(data[0]) // 2
 		hplmn = enc_plmn(mcc, mnc)
 		content = hplmn + access_tech
 		data, sw = self._scc.update_binary(EF['OPLMNwAcT'], content + 'ffffff0000' * (size/5-1))
@@ -101,7 +101,7 @@
 		"""
 		# get size and write EF.PLMNwAcT
 		data = self._scc.read_binary(EF['PLMNwAcT'], length=None, offset=0)
-		size = len(data[0])/2
+		size = len(data[0]) // 2
 		hplmn = enc_plmn(mcc, mnc)
 		content = hplmn + access_tech
 		data, sw = self._scc.update_binary(EF['PLMNwAcT'], content + 'ffffff0000' * (size/5-1))
@@ -109,7 +109,7 @@
 
 	def update_plmnsel(self, mcc, mnc):
 		data = self._scc.read_binary(EF['PLMNsel'], length=None, offset=0)
-		size = len(data[0])/2
+		size = len(data[0]) // 2
 		hplmn = enc_plmn(mcc, mnc)
 		data, sw = self._scc.update_binary(EF['PLMNsel'], hplmn + 'ff' * (size-3))
 		return sw
@@ -127,7 +127,7 @@
 			raise RuntimeError('unable to calculate proper mnclen')
 
 		data = self._scc.read_binary(EF['AD'], length=None, offset=0)
-		size = len(data[0])/2
+		size = len(data[0]) // 2
 		content = data[0][0:6] + "%02X" % mnclen
 		data, sw = self._scc.update_binary(EF['AD'], content)
 		return sw
diff --git a/pySim/commands.py b/pySim/commands.py
index 385cacf..ff64ed2 100644
--- a/pySim/commands.py
+++ b/pySim/commands.py
@@ -49,11 +49,11 @@
 		# what we get in the length field.
 		# See also ETSI TS 102 221, chapter 11.1.1.3.0 Base coding.
 		exp_tlv_len = int(fcp[2:4], 16)
-		if len(fcp[4:])/2 == exp_tlv_len:
+		if len(fcp[4:]) // 2 == exp_tlv_len:
 			skip = 4
 		else:
 			exp_tlv_len = int(fcp[2:6], 16)
-			if len(fcp[4:])/2 == exp_tlv_len:
+			if len(fcp[4:]) // 2 == exp_tlv_len:
 				skip = 6
 
 		# Skip FCP tag and length
@@ -108,7 +108,7 @@
 		return rv
 
 	def select_adf(self, aid):
-		aidlen = ("0" + format(len(aid)/2, 'x'))[-2:]
+		aidlen = ("0" + format(len(aid) // 2, 'x'))[-2:]
 		return self._tp.send_apdu_checksw(self.cla_byte + "a4" + "0404" + aidlen + aid)
 
 	def read_binary(self, ef, length=None, offset=0):
@@ -126,7 +126,7 @@
 		if not hasattr(type(ef), '__iter__'):
 			ef = [ef]
 		self.select_file(ef)
-		pdu = self.cla_byte + 'd6%04x%02x' % (offset, len(data)/2) + data
+		pdu = self.cla_byte + 'd6%04x%02x' % (offset, len(data) // 2) + data
 		return self._tp.send_apdu_checksw(pdu)
 
 	def read_record(self, ef, rec_no):
@@ -143,10 +143,10 @@
 		r = self.select_file(ef)
 		if not force_len:
 			rec_length = self.__record_len(r)
-			if (len(data)/2 != rec_length):
-				raise ValueError('Invalid data length (expected %d, got %d)' % (rec_length, len(data)/2))
+			if (len(data) // 2 != rec_length):
+				raise ValueError('Invalid data length (expected %d, got %d)' % (rec_length, len(data) // 2))
 		else:
-			rec_length = len(data)/2
+			rec_length = len(data) // 2
 		pdu = (self.cla_byte + 'dc%02x04%02x' % (rec_no, rec_length)) + data
 		return self._tp.send_apdu_checksw(pdu)
 
diff --git a/pySim/transport/serial.py b/pySim/transport/serial.py
index f672be2..11fcd6a 100644
--- a/pySim/transport/serial.py
+++ b/pySim/transport/serial.py
@@ -213,7 +213,7 @@
 			self._tx_string(pdu[5:])
 
 		# Receive data (including SW !)
-		#  length = [P3 - tx_data (=len(pdu)-len(hdr)) + 2 (SW1/2) ]
+		#  length = [P3 - tx_data (=len(pdu)-len(hdr)) + 2 (SW1//2) ]
 		to_recv = data_len - len(pdu) + 5 + 2
 
 		data = ''